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Full text of "An introduction to entomology, or, Elements of the natural history of insects : with plates"

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AN 



INTRODUCTION 



TO 



ENTOMOLOGY: 



OR 




ELEMENTS 



OF THE 



NATURAL HISTORY OF INSECTS 

WITH PLATES. 



By WILLIAM KIRBY, M.A. F.R. and L.S. 

RECTOR OF BARHAM, 
AND 

WILLIAM SPENCE, Esq. F.L.S. 



VOL. III. 



LONDON: 

PRINTED FOR 

LONGMAN, REES, ORME, BROWN, AND GREEN, 
1'ATERNOSTER ROW. 

1826. 



v,V3> 



PBINTED BY KICHARfc TAYLOR, 
SHOE LANE, LONBON. 



ADVERTISEMENT. 



J. HE publication of the concluding- volumes of 
the cc Introduction to Entomology" has been un- 
avoidably delayed by the continued ill health of 
one of the Authors, which has devolved upon the 
other a considerable increase of labour, and de- 
manded a greater expenditure of time than would 
otherwise have been required : for though Mr. 
Spence put every facility in Mr. Kirby's power, 
and had drawn up a rough copy of every Letter 
belonging to his department ; yet, as most of 
them had been written several years ago, many 
curious facts,, and a great variety of interesting- 
information subsequently derived from various 
sources, were necessarily to be inserted, and the 
whole to be prepared for the press. 

When the thousands of objects that were to be 
examined, and many of them repeatedly, in com- 
posing the Letters on the External Anatomy of 
Insects, are considered, it will not appear sur- 



iv ADVERTISEMENT. 

prising* if some errors should have crept in; espe- 
cially as Mr. Kirby was deprived of the effectual 
help formerly derived from the acumen, learning, 
and judgement of his esteemed coadjutor, by his 
lamented and protracted indisposition : but it is 
hoped that these errors will be found of minor 
importance, and not to affect any general prin- 
ciples advanced. The same remarks are also in 
part applicable to the Anatomical and Orismolo- 
gical Tables (Vol. III. p. 354—393, and Vol. IV. 
p. 257 — 354), which were drawn up by the Au- 
thors jointly many years ago, before any other 
portion of the work was composed, but which 
have, especially the former, required considerable 
alterations and additions in consequence of sub- 
sequent observations and information. 

It will not be amiss here to state, in order to 
obviate any charge of inconsistency in the pos- 
sible event of Mr. Kirby's adverting in any other 
work to this subject, that though on every material 
point the authors have agreed in opinion, their 
views of the theory of instinct do not precisely 
accord. That given in the second and fourth 
volumes is from the pen of Mr. Spence. 

It was originally intended, as mentioned in the 
Preface, to have given a complete list of Entomo- 



adVe 



ERTISEMENT. 



logical works,, of which a large portion was drawn 
up; but the great length to which more important 
matters have extended, has rendered necessary 
the intire omission of this list, — an omission in 
some degree compensated by the catalogue of 
Authors quoted, which comprises most of the 
standard Entomological works. 



ERRATA. 

Page. Line, 

29 27, for Pseudo-cordia read Pseudo-cardia. 

33 7,/o>- -rV read If. 

35 7 and elsewhere, for Gigas read grandis. 

46 16, for number and situation read in some respects. 

98 6, for Furtina read Jurtina. 

121 note d , for c read cf. 
135 note b , for XXIV. read XXIII. 
137 note a , for 17 read 18. 
251 4, for ten read nine. 

' i for frcenum read fraenum. 
359 21, S 

422 note b , for a' read a". 

425 note b , for b" read b'. 

471 1, defe Pelecotoma. 

10, for orbicular read subtriangular. 

512 antepenult. After genera insert except in some A cridce, as A.viri- 

dissima. 

562 note c , for 9rvta read tfvv/u.1. 

606 5, for Heteropteious read Homopterous. 



DIRECTIONS TO THE BINDER. 

The Synoptical Table of the Nomenclature of the Parts of the 
External Crust of Insects should be placed opposite to page 354. 

Plates VI — XX. should be placed in this Volume, and the re- 
mainder in the Fourth. 

It is however suggested to Purchasers, that in binding complete 
Sets of the Work, a separate Volume may be formed of the Synop- 
tical Table, the Plates and their Explanations, and the Indexes. 



CONTENTS OF VOL. III. 



Letter. Page. 

XXVIII. Definition of the Term Insect 1—51 

XXIX. States of Insects. Egg state 52 — 104< 

XXX. The same Subject continued. Larva 

state 105—237 

XXXI. The same Subject continued. Pupa 

state 238—290 

XXXII. The same Subject continued. Imago 

state 291—347 

XXXIII. External Anatomy of Insects. Terms 

and their Definition. 348 — 393 

XXXIV. The same Subject continued. The Head 

and its Parts 394—528 

XXXV. The same Subject continued. The 

Trunk and its Parts and Organs . . 529 — 697 
XXXVI. The same Subject continued. The Ab- 
domen and its Parts 698 — 720 



NOTICE RESPECTING VOL. I. and II. 

It being judged expedient, since the publication of the last Edition of 
the first and second Volumes of this Work, to adopt a new plan with 
respect to the reference letters of the Plates, the Reader is requested to 
make the following corrections in those Volumes. 







Vol. I. 


Page. 


Note. 


125 


e 


for f, d read a". 


273 


a 


for a read a. 


395 


a 


for 29, 30 read 13. 

Vol. II. 


244 


c 


for a read a. 


319 


b 


for 10 read 14. 


348 


a 


for a read e"'. 


353 


a 


for 7 — . read 16 — . 


366 


b 


for a read s", v'". 




c 


for b read t". 


405 


a 

9 


for 1.8. aa read 18. cf. 




b 


for bb read q". 


406 


e 


for bb read C". 


407 


c 

> 


force read C" C", which represent the bundles of mus- 
cles in connexion with the drums. In the above figure 
the mirror is the part directly under those bundles. 



AN 

INTRODUCTION 



TO 



ENTOMOLOGY. 



LETTER XXVIII. 



DEFINITION OF THE TERM INSECT. 

W HAT is an insect ? This may seem a strange ques- 
tion after such copious details as have been given in my 
former Letters of their history and economy, in which it 
appears to have been taken for granted that you can an- 
swer this question. Yet in the scientific road which you 
are now about to enter, to be able to define these crea- 
tures technically is an important first step which calls for 
attention. You know already that a butterfly is an insect 
— that a fly, a beetle, a grasshopper, a bug, a bee, a. 
louse, and flea, are insects — that a spider also and centi- 
pede go under that name; and this knowledge, which 
every child likewise possesses, was sufficient for compre-. 
hending the subjects upon which I have hitherto writte,n. 
But now that we ai*e about to take a nearer view of thern — ■ 
to investigate their anatomical and physiological charac- 

VOL. JTI, B 



2 DEFINITION OF THE TERM IXSECT- 

ters more closely — these vague and popular ideas are 
insufficient. In common language, not only the tribes 
above mentioned, but most small animals — as worms, 
slugs, leeches, and many similar creatures, are known by 
the name of insects. Such latitude, however, cannot be 
admitted in a scientific view of the subject, in which the 
class of insects is distinguished from these animals just as 
strictly as beasts from birds, and birds from reptiles and 
amphibia, and these again from fishes. Not, indeed, 
that the just limits of the class have always been clearly 
understood and marked out. Even when our corre- 
spondence first commenced, animals were regarded as 
belonging to it, which since their internal organization 
has been more fully explained, are properly separated 
from it But it is now agreed on all hands, that an 
earthworm, a leech, or a slug, is not an insect; and a 
Naturalist seems almost as much inclined to smile at 
those who confound them, as Captain Cook at the island- 
ers who confessed their entire ignorance of the nature of 
cows and horses, but gave him to understand that they 
knew his sheep and goats to be birds. 

You will better comprehend the subsequent definition 
of the term Insect, after attending to a slight sketch of 
the chief classifications of the animal kingdom, more es- 
pecially of the creatures in question, that have been pro- 
posed. That of Aristotle stands first. He divides ani- 
iuals into two grand sections, corresponding with the Ver- 
teC'rata and Invertebrata of modern Zoologists : those, 

namely, that have blood, and those that have it not a : 

i>y this it appears that he only regarded red blood as 
red blood ; and probably did not suspect that there was 

1 Eu&ifiK, Avetiftct. Hist. Animal. 1. i. c. 6. 



DEFINITION OF THE TERM INSECT. & 

a true circulation in his Mollusca and other white-blooded 
animals. His Enaima, or animals that have blood, he 
divides into Quadrupeds, Birds, Fishes, Cetacea, and 
Apods or reptiles ; though he includes the latter, where 
they have four legs, amongst the quadrupeds 3 ; and his 
Anaima, or animals without blood, into Malachia, Ma- 
lacostraca, Oslracoderma, and Entoma. The first of 
these, the Malachia, he defines as animals that are ex- 
ternally fleshy and internally solid, like the Enaima ; and 
he gives the Sepia as the type of this class, which answers 
to the Cephalopoda of the moderns. The next, the Ma- 
lacostraca, synonymous with the Crustacea of Cuvier and 
Lamarck, are those, he says, which have their solid part 
without and the fleshy within, and whose shell will not 
break, but splits, upon collision b . The Oslracoderma, cor- 
responding with the Testacea of Linne, he also defines as 
having their fleshy substance within, and the solid with- 
out; but whose shell, as to its fracture, reverses the cha- 
racter of the Malacostraca. He defines his last class 
Entoma, in Latin Insecta, with which we are principally 
concerned, as animals whose body is distinguished by in- 
cisures, either on its upper or under side, or on both, and 
has no solid or fleshy substance separate, but something 
intermediate, their body being equally hard both within 
and without . This definition would include the Anne- 
lida and most other Vermes of Linne, except the Testacea, 
which accordingly were considered as insects by those 
Zoologists that intervened between Aristotle and the lat- 
ter author. The Stagyrite, however, in another place, 

a Hist. Animal. 1. i. c.5,6: compare 1. v. c. 3 and 83, and Be 
Partibus Animal. I. iv. c. 1 and 11. 

b To Is ok>.y)(>ov etvruv a Sgctwrov «XA« <p7\ctT0V. 
c Hist. Animal. 1. iv. c. 1. 

B 2 



4 DEFINITION OF THE TERM INSECT. 

has expressly excluded all apods \ From other passages 
in his works, it appears that he regarded the Vermes, &c. 
either as larva;, or as produced spontaneously and not 
ex ovo b . 

This definition of an insect, though partly founded on 
misconception, as well as his primary division of animals 
in general, is by no means contemptible. If you look at 
a bee or a fly, you will observe at first sight that its body 
is inserted, being divided as it were into three principal 
pieces — head, trunk, and abdomen ; and if you examine 
it more narrowly, you will find that the two last of these 
parts, especially the abdomen, are further subdivided. 
And this character of insertion, or division into segments, 
more or less present in almost every insect d , is not to be 
found (with the exception of the Crustacea, which Ari- 

a 'Ru'TSftot iro\vzohei y.iu yotq srt vocvrx. De Part. Animal. 1. iv. C. 6. 

h Hist. Animal. 1. iv. c. 19. 

c The insection that distinguishes these parts, the abdomen espe- 
cially, is most visible in the majority of the Hyvienoptcra and Diptera 
orders ; next in some Coleoptera, as the Lamellicorn tribes, &e. and 
the Lepidoptera. Latreille is of opinion, that the two last segments 
of the thorax in some insects are represented by the first of the 
abdomen, and that the upper half segment of this part in Coleoptera 
also represents the same. Latr. De quelques Appendices, &c. An- 
nates Generates des Sciences Physiques. A Bruxelles, vi. livrais. xviii. 
14. In fact, in the Lepidoptera, when the abdomen is separated from 
the trunk, this segment usually remains attached to the latter. In 
the Myriapods, the trunk is to be distinguished from the abdomen 
only by its bearing the three first pair of legs. 

d There is no general rule without exceptions, and no character is 
so universal as to be distinctly exhibited by every member of a class 
or other natural group. Thus, in the majority of the mites (Acarus 
L.) the body is marked by no segments, and the only articulation or 
incision is in the legs, palpi, &c. But as the exception does not make 
void the rule, so neither does the extenuation or absence of some 
primary character at its points of junction with others, in some indi- 
viduals, annihilate the class or group. 



Definition of the term insect. 5 

stotle distinguishes by the nature of their integument 
and its contents) in any of the other classes into which 
he divided animals without blood. It was on account of 
this most obvious of their characters, that these little 
creatures were in Greek named Entoma, and in Latin 
Insecta ,• and from the former word, as you know, our 
favourite science takes the name of Entomologij. 

Pliny adhering to the definition of Aristotle, as far as 
it relates to the insertion of the animals we are speaking 
of, expressly includes A_pods, as well as Aptcra, amongst 
them a ; and in this was followed, without any attempt at 
improvement, by all the entomological writers that inter- 
vened between him and the great Aristotle of the mo- 
derns, Linne. 

This illustrious naturalist, aware of the incorrectness 
of the primary divisions of the animal kingdom founded 
upon the presence or absence of blood, establishes his 
system upon the structure of the heart, and upon the 
temperature and colour of the circulating fluid. He di- 
vided animals into two great sections or sub-kingdoms, 
each comprising two classes. YWsJirst section included 
those having a heart with tivo ventricles, txvo auricles, 
and 'warm and red blood, viz. the Mammalia or beasts, 
and the Aves or birds. His second, those having a heart 
with one ventricle, one auricle, and cold and red blood, 
namely, the classes Amphibia, which included reptiles, 
serpents, &c. and Pisces or fish. I lis third, those having 
a heart with one ventricle and no aurxle, and cold white 
sanies in the place of blood, namely, his classes Insecta 
et Vermes, including the Invertebrate animals of La- 

■'- Hist. Xat. I xl c. 1 . 



6 DEFINITION OF THE TERM INSECT. 

marck. Thus the first of Aristotle's great divisions he 
increased by the addition of a new and very distinct class, 
the Amphibia, by which some ground was gained in the 
science ; but as much was lost by his compressing the 
four classes of which the last consisted into two, by which 
the natural classes of Cephalopoda and Crustacea merged 
under Insecta and Vermes. Linne was not aware of the 
extraordinary fact, that the Cephalopoda have three 
hearts; and that though the Crustacea and Arachnida 
have a circulation, Insects have none, or he would never 
have taken this retrograde step. 

Indeed Linne's definition of an Insect is, in many 
most material points, inapplicable, not only to the Crus- 
tacea, but to many other animals included under that 
denomination. This will appear evident from a very 
slight examination. Thus it runs : " Polypod animal- 
cula, breathing by lateral spiracles, armed every 'where 
with an osseous skin, whose head is furnished with mov- 
able sensitive antenna*" Now of this definition only 
the first member can be applied to the whole class which 
it is meant to designate; for the entire genus Cancer L., 
which, with some others, forms the class Crustacea of the 
moderns, does not respire by spiracles at all, but by gills ; 
and the same in some degree may be said of spiders, 
scorpions, &c. With the last member of the definition 
Linne himself must have been aware that a large number 
of what he conceived to be insects were at variance, as 
mites, spiders, and many other of his apterous tribes : 
though from some very recent observations of M. La- 

a Animalcula polypoda, spiracidis lateralibus respirantia, cute 
ossea eataphracta; antennis mobilibus sensoriis instruuntur. Syst. 
Nat, ed. 12. i. 533. 



DEFINITION OF THE TERM INSECT. 7 

treille a , there seems some ground for thinking, that in 
these the antennae are represented by the mandibles, 
palpi, &c. b , and to the soft flexible, coriaceous or mem- 
branous skin of a vast number of insects, the term cutis 
ossea is by no means applicable. 

Evident as these incongruities are, when the Herculean 
task which Linne imposed upon himself, and the vastness 
and variety of his labours, are considered, they become 
very venial. Indeed, unless he had divided his class In- 
secta into two or more, it was impossible to define it in- 
telligibly to ordinary readers, otherwise than nearly in 
the terms which he actually employed ; and these cha- 
racters, restricted and amended by qualifying clauses, are 
still those to which recurrence must be had in a popular 
definition of the class, when separated as it ought to be 
from the Crustacea and Arachnida. 

Pennant, Brisson, and other zoologists, who, attending 
to nature rather than system, saw the impropriety of unit- 
ing a crab or a lobster in the same class with a bee or a 
beetle, long since assigned the Crustacea their ancient 
distinct rank. " But these changes," as Latreille ob- 
serves , " being only founded upon external characters, 
might be deemed arbitrary ; and to fix our opinion, it 
was necessary to have recourse to a decisive authority — 
the internal and comparative organization of these ani- 

a Quoted by Mr, Wm. MacLeay in his very remarkable and 
learned work Horcc Entomological, in which he inclines to the same 
opinion. 383. 

b Treviranus ( Ueber den innem Ban der Aracknidcn, &c. 22.) al- 
ways calls the palpi of spiders " Fiilhorner." In Scorpio he regards 
them as palpi (Palpen). 

c N. Diet. d'Hist. Nat. xvi. 18!. 



8 DEFINITION OF THE TERM INSECT. 

mals. It results from the observations of the most pro- 
found comparative anatomist of our age, M. Cuvier, that 
the Crustacea and Arachnida differ from insects properly 
so called, and particularly from those that are furnished 
with wings, in having a complete system of circulation, 
a different mode of respiration, and that they have a more 
perfect organization. Influenced by these motives, both 
Cuvier and Lamarck have considered them as forming 
two classes separate from insects. Treviranus, led by 
considerations founded on the organs of circulation, of 
respiration, and of generation, is of opinion that spiders 
and scorpions ought to form one class with the Crustacea : 
he observes, however, that the nervous system of all three 
is very dissimilar ; and that in an arrangement founded 
on this circumstance, the organs of motion, and the ex- 
ternal shape, even spiders and scorpions must be placed 
in different classes a . 

It is to be observed with regard to the Arachnida of 
the French school, that the class as laid down by them 
includes several animals that have no circulation, and 
breathe by trachece, of which description are the mites 
{Acarus L.), and the harvest-men (Phalangium L.) &c. ; 
and therefore it has been divided into two orders, Pul- 
•monaria and Tracheana ; but if the definition from the 
internal organization be adhered to, the latter should 
either remain with the class Insecta, or form a new one by 
themselves. Yet the animals that compose the Trachean 
order of Arachnida, their external form considered, are 
certainly much more nearly related to the spiders and 

a Treviranus, ut supra, 48. For the nervous system of scorpions, 
see t. \.f. 13 ; and for that of spiders, /. \.f. 45. 



DEFINITION OF THE TERM INSECT. 9 

scorpions than to any members of the class Insecta at 
present known. This circumstance, perhaps, may seem 
to throw some doubt upon the modern system of classi- 
fication. 

I must further observe, that the assertion of Treviranus, 
which appears to intimate that the respiration of the pul- 
monary Arachnida is the same with that of the Crustacea, 
is not quite correct, since in the latter the branchial or 
mils are external, and in the former internal, the air en- 
tering by spiracles before it acts upon them a . 

It may not be amiss in this place to lay before you die 
principal points in which the Crustacea and Arachnida 
agree with Insecta, and also those in which they differ. 

The Crustacea agree with Insecta in having a body 
divided into segments, furnished with jointed legs, com- 
pound eyes, and antennae. Their nervous system also is 
not materially different, and they are both oviparous. 
They differ from them in having the greater insertions 
of the body less strongly marked; in the greater num- 
ber of legs on the trunk, the anterior ones perform- 
ing the office of maxillae; in their eyes usually on a 
moveable footstalk ; their palpigerous mandibles ; and 
their four antennae at least in the great majority. But 
the principal difference consists in the internal organi- 
zation and the fountains of vitality; for the Crustacea have 
a double circulation, the fountain of which is a heart in 
the middle of their thorax b . They have too a kind of 
gizzard and liver, at least the Decapods c , and their re- 
spiration is by gills, Genuine insects terminate their 

a Plate XXIX. Fig. 2. Treviranus, t. If. 1. 

» Cuvier Anal, Cowp, iy. -107- c A" Diet, d'Hist. Nat. ix, IPO. 



10 DEFINITION OF THE TERM INSECT. 

existence after they have laid their eggs a ; but the Crus- 
tacea live longer, and lay more than once. 

The Arachnida will be found to diner from insects 
more widely than even the Crustacea. They agree in 
their jointed legs and palpi ; immoveable eyes ; and in 
being covered with a coriaceous or corneous integument: 
but they differ in having a system of circulation; gills 
instead of trachea? ; their organs of generation double ; 
and the females lay more than once in their lives. Their 
head also is not distinct from the trunk as in insects ; 
they have no compound eyes ; and their antenna?, if we 
admit the opinion on this head of MM. Latreille and 
Treviranus, that they have representatives of these or- 
gans, differ totally in structure, situation, and use, from 
those of the great body of insects. In the Araneidce or 
Spiders, their body seems to have no segments or incisure 
but that which separates the abdomen from the trunk ; 
and in the Scorpiotiidce they are observable only in the 
abdomen. Other particulars might be enumerated in 
which these two classes differ from insects; but these will 
be sufficient to convince you that Aristotle and MM. Cu- 
vier and Lamarck were justified in separating them. 

The two last-mentioned authors made further improve- 
ments in Zoology. The latter, from the consideration of 
the general structure of animals, perceiving that Aristo- 
tle's Enaima were distinguished from his A?iaima, by 
being built as it were upon a vertebral column, very ju- 
diciously changed the denomination, which was indeed 
improper, of " The Philosopher' £' two sub-kingdoms, into 

a The females of Dorthesia, however, a genus related to Coccus, are 
said to survive laying their eggs. N. Diet. d'Hist. Nat. ix. 553. 



DEFINITION OF THE TERM INSECT. 



11 



that of Vertebrata or animals that have a vertebral co 
lumn, and Invertebrata or those that have no vertebral 
column. These he distributes into three primary divi- 
sions according to their supposed degrees of intelligence 
— Thus : 

* Apathetic Animals. 1. Infusoria. 

2. Polypi. 

3. Radiata. 
4*. Vermes. 

* * Sensitive Animals. (Epizoaria.) 

5. Insecta. 

6. ArachnidA. 

7. Crustacea. 

8. Annelida. 

9. Cirrhipeda. 
10. mollusca. 

*** Intelligent Animals. 11. Pisces. 

12. Reptilia. 

13. Aves. 

14. Mammalia. 1 
Profiting by the light afforded by the Aristotelian sy- 
stem, this eminent zoologist improved, we see, upon that 
of Linne, by resolving his Insecta into three classes, and 
his Vermes into seven, interposing the Linnean Insecta 
between the four first and three last, in which he was 
not so happy, since as to sense insects should certainly 
occupy the place he has here assigned to the Mollusca. 

In the work from which I have taken this statement 
of Lamarck's system, that acute writer has given a sketch 
of another method of arrangement, in which he has made 
the first deviation from the beaten track of an unbroken 



a Atilm, sans Vertebr. i. 381. 



12 DEFINITION OF THE TERM INSECT. 

and unbranching series. In the Supplement to the first 
volume, he has distributed the Invertebrata in a double 
subramose series — one consisting of articulate ', and the 
other of inarticulate animals 3 . 

Upon Lamarck's system, most of the modern ones, 
with some variation, are founded. There is one, how- 
ever, by a learned countryman of ours, that is more 
unique, sui generis, and I may add profound, than any 
that has yet appeared. I am speaking of that, you will 
perceive, of which our friend Mr. Win, MacLeay has 
given a detailed statement in his Horce Entomologies. 
In this he goes even far beyond what Lamarck has at- 
tempted in the above sketch, and substantiates his claim 
to be considered as one of those original thinkers, rari 
nantes in gurgite vasto, that do not appear every day. 
The following are the principal bases of his system. 

1. That all natural groups, whether kingdoms or any 
subdivision of them, return into themselves ; a distribu- 
tion which he expresses by circles. 

2. That each of these circles is formed precisely of 
Jive groups, each of which is resolvable into five other 
smaller groups, and so on till you reach the extreme term 
of such division. 

3. That proximate circles or larger groups are con- 
nected by the intervention of lesser groups, which he de- 
nominates osculant. 

4. That there are relations of analogy between the 
corresponding points of contiguous circles. 

This system he has represented by tables of circles 
inscribed with the five primary divisions of each group. 
His first table exhibits a general view of organized matter 

a Anim. sans Vertebr. i, 457. 



DEFINITION OF THE TERM INSECT. 1 

as distributed in the animal and vegetable kingdoms- 
Thus : 




Our learned author here divides the animal kingdom 
into what may be denominated five sub-kingdoms or pro- 
vinces, in three of which (with the exception of the Crus- 
tacea and Aracknida belonging to his Annulosa) no cir- 
culation of blood is visible, but which obtains in the rest. 
These he names — 

1. Acrita, consisting of the Infusory Animals, the 
Polypi, the Corallines, the Tcsnice, and the least organized 
of the Intestinal Worms. 

2. Radiata, including the Jelly-jish, Starfish, Echini, 
and some others. 

3. Annulosa, consisting of Insect a, Arachnida, and 
Crustacea. 

4. Vertebrata, consisting of Beasts, Birds, Reptiles, 
Amphibia, and Fishes. 

5. Mollusca, including the numerous tribes of shell- 
fish, land-shells, slugs, &c, which, from their mucous or 

gelatinous substance, from their nervous system and the 
imperfection of their senses, return again to the Acrita, 



14" DEFINITION OF THE TERM INSECT. 

though connected with the Vertebrata by having a heart 
and circulation. 

His next set of circles shows the sub-division of these 
five sub-kingdoms into classes — Thus : 



/*♦* 



/ 






^ 



'P.rudes 



f 

*& 



P.vaginat7\ 



IcepJiuTa P«roj>od*Z pUm 



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In this scheme the osculant classes are those placed 
between the circles. In the Mollusca circle two classes 
are still wanting to complete the quinary arrangement 
of that sub-kingdom. I am not sufficiently conversant 



DEFINITION OF THE TERM INSECT. 15 

with the details of the animal kingdom at large to hazard 
any decided opinion upon Mr. MacLeay's whole system, 
or to ascertain whether all these classes are sufficiently 
distinct 3 . My sentiments with regard to those of the 
Annulosa I shall state to you hereafter. 

Upon a future occasion I shall consider more at large 
the station to which insects seem entitled in a system of 
invertebrate animals, which will not accord exactly with 
that assigned by MM. Cuvier and Lamarck. But I am 
now in a field in which I have no intention to expatiate 
further, than as it is connected with the subject of the 
present letter. I shall therefore confine myself in what 
I have more to say to the definitions of Insecta that have 
been given by modern authors, beginning with that of 
the zoologist last mentioned. Insects form a part of his 
second group, which he terms sensitive animals [animaux 

sensibles), which group he thus defines : " They are sen- 
tient, but obtain from their sensations only perceptions 
of objects — a kind of simple ideas which they cannot 
combine to obtain complex ones. Charact. No vertebral 
column ; a brain, and most commonly an elongated me- 
dullary mass ; some distinct senses; the organs of move- 
ment attached tinder the skin : form symmetrical, by 
parts, inpairs b ." This division of animals, from the 

1 The number Jive, which Mr. MacLeay assumes for one basis of 
his system as consecrated in Nature, seems to me to yield to the 
number seven, which is consecrated both in Nature and Scripture. 
Metaphysicians reckon seven principal operations of the mind ; mu- 
sicians seven principal musical tones; and opticians seven primary 
colours. In Scripture the abstract idea of this number is — comple- 
tion-r-fullness — perfection. I have a notion, but not yet sufficiently 
matured, that Mr. MacLeay's quinaries are resolvable into septenaries. 

b Anim.sans Vertebr.'i. 381. 



16 DEFINITION OF THE TERM WSECT'. 

kind and degree of sense and intelligence that they pos- 
sess, seems rather fanciful than founded in nature, since 
many insects show a greater portion of them than many 
vertebrate animals. Compare in this respect a bee with 
& tortoise*. Lamarck divides his group oianimaux sen- 
sible?; into two sections, namely, Articulated animals, ex- 
hibiting segments or articulations in all or some of their 
parts ; and Inarticulated animals, exhibiting neither seg- 
ments nor articulations in any of their parts. Insecta, 
Arachnida, and Crustacea, belong to the first of these 
sections, which he defines as " those whose body is di- 
vided into segments, and which are furnished, with jointed, 
legs bent at the articulations 1 '." Insecta he defines — 
" Articulate animals, undergoing various metamorphoses, 
or acquiring new kinds of parts — having, in their perfect 
state, six feet, two antenna, two compound eyes, and a 
corneous skin. The majority acquiring wings. Respira- 
tion by spiracles (stigmates), and two vascular opposite 
chords, divided, by plexus, and constituting aeriferous tra- 
chea:, which extend, every where. A small brain at the 
anterior extremity of a longitudinal knotty marrow, with 
nerves. No system of, circulation, no conglomerate glands. 
Generation oviparous : two distinct sexes. A single sex- 
ual union in the whole course oflife c ." Arachnida he 
defines — " Oviparous animals, having at all times jointed 
legs, undergoing no metamorphosis, and never acquiring 
new kinds of parts. Respiration tracheal or branchial : 
the openings for the entrance of the air spiraculiform 
(stigmatiformes). A heart and. circulation beginning in 

n See on this point MacLeay, Hor. Entomolog. 209— . 

b Anhri. sans Vertebr. iii. 243. <■• JhUl. iii. 243 



DEFINITION OF THE TERM INSECT. 17 

many. The majority couple often in the course of life*." 
I shall next add his definition of Crustacea : " Ovipa- 
rous, articulated, apterous animals, with a crustaceous in- 
tegument more or less solid, having jointed legs ,• eyes 
either pedunculate or sessile, and most commonly four 
antenna:, with a maxilliferous mouth seldom rostriform ; 
maxilla: in many pairs placed one over the other ; scarcely 
any under-lip ; no spiracuhform openingsfor respiration ,• 
five or seven pair of legs ,• a longitudinal knotty marrow 
terminated anteriorly by a small brain. A heart and ves- 
sels for circulation. Hespiration branchial with external 
branchicc, sometimes hid under the sides of the shell of the 
thorax, or shut in prominent parts ; sometimes uncovered, 
and in general adhering to partiadar legs or to the tail t 
Each sex usually double^." 

I have given Lamarck's definitions of these three classes, 
all considered as Insecta by Linne, that by comparing 
them together you may be better enabled to appreciate 
the system of this author. On looking over the characters 
of the Arachnida as here given, you will see at once that 
it consists of heterogeneous animals — for in fact he in- 
cludes in this class not only the Trachean Arachnida of 
Latreille, but the Ametabolia of Dr. Leach, or the Hexa- 
pod Aptera, and the Myriapoda. 

I shall next copy for you Latreille's latest definition of 
Insecta and Arachnida. 

" Insecta : A single dorsal vessel representing the 
heart : two trunks of trachea running the whole length 
of the body, and opening externally by numerous spira- 
cles; two antenncB ; very often upper appendages for 
flight, indicating the metamorphosis to which the animal 

* Anim. tans Vertebr. iii. 245. b Ibid. 

VOL. III. C 



18 DEFINITION OF THE TERM INSECT. 

is subject when young ; legs most commonly reduced to 
six. Arachnida: Distinguished from Crustacea by 
having their respiratory organs always internal, opening 
07i the sides of the abdomen or thorax to receive the re- 
spirablefuid. Sometimes these organs perform the office 
of lungs, and then the circulation takes place by means of 
a dorsal vessel, which sends forth arterial, and receives 
venose branches. Sometimes they are trachea or air- 
vessels, which, as in the class Insecta, replace those of 
circulation. These have only the vestige of a heart, or a 
dorsal vessel alternately contracting and sending forth 
no branch. The absence of antennae, the reunion of the 
head with the thorax, a simple trachea but ramified and 
almost radiating, serve to distinguish these last Arachnida, 
or the most imperfect of insects, which respire only by 
trachea*." Under this head he observes — " Of all 
these characters, the most easy to seize and the most 
certain would doubtless be, if there were no mistake in it, 
that of the absence of antennae ; but later and compara- 
tive researches, confirmed by analogy, have convinced 
me, that these organs, under particular modifications it 
is true, and which have misled the attention of naturalists, 
do exist b :" and he supposes, from the situation and di- 
rection of the mandibles of the Arachnida, corresponding 
with that of the intermediate pair of antennce in Crustacea, 
that they really represent the latter organs. If this sup- 
position be admitted, their use is wholly changed; the palpi, 
in fact, executing the functions of antennas, which proba- 
bly induced Treviranus to call them Filhlhorner (Feeling- 

a Des Rapports gen'eraux, §c. det Anim. invertebr. artic, Ann. du 
Mus. 

b Ibid. Hor. Entomolocr. 383, 



DEFINITION OF THE TERM INSECT. 19 

horns). Perhaps these last may be regarded as in some 
sort representing the external antennae of the Crustacea ? 
With regard to Insecta, their antennas seem to disappear 
in the PupiparcB Latr., or the genus Hippobosca L. 

The above definitions of the Arachnida by these two 
celebrated authors, appear to me the reverse of satisfac- 
tory. When we are told of animals included in it, that 
some breathe by gills and others by tracheae, that some 
have a heart and circulation and others not, we are im- 
mediately struck by the incongruity, and are led to sus- 
pect that animals differing so widely in the fountains of 
life ought not to be associated in the same class. A 
learned zoologist of our own country, Dr. Leach, seems 
to have made a nearer approach to a classification in ac- 
cordance with the internal organization, by excluding 
from Arachnida the Acari and Mijriapoda. 

Sub-kingdom Annulata Cuv. 

* Gills for respiration. Classes. 

Legs sixteen; .... Antennas two or four 1 Crustacea. 

** Sacs for respiration. 
Legs twelve : .... Antennae none 3 Arachnoidea, 

*** Trachea? for respiration, 
•a. No Antenna?. 

4 Acari. 

b. Two Antenna?. 

Six thoracic legs : Abdomen also bearing legs 2 Myriapoda. 

Six thoracic legs : No abdominal legs 5 Insecta*. 

Mr. MacLeay, on whose system I shall now say a few 
words, divides his sub-kingdom Annulosa into five classes, 
namely, Crustacea, Ametabola, Mandibulata, Haustellata, 
Arachnida. From the Crustacea he goes by the genus 

* Leach in Entomologists Useful Compendium, by Samouelle, 75. 
c 2 



20 DEFINITION OF THE TERM INSECT. 

Porcellio Latr. to Iidus z , which begins his Ametabola: 
these he connects with the Mandibidata, by Nirmas, 
which he thinks approaches some of the corticarious 
Coleoptera h . This class he appears to leave by the Tri- 
choptera Kirby, and so enters his Haustellata by the Le- 
pidopterd c , and leaves it again by the Diptera by means 
of the Pupiparce Latr., especially Nyctwibia, connecting 
this class with the Aracknida, which he enters by the 
Hexapod Acari L. d , and these last he appears to leave 
by the Araneidce, and to enter the Crustacea by the De- 
capods e : thus making good his circle of classes, or a 
series of Annulose animals returning into itself. Mr. 
MacLeay's whole system upon paper appears very har- 
monious and consistent, and bears a most seducing aspect 
of verisimilitude ; but it has not yet been so thoroughly 
weighed, discussed, and sifted, as to justify our adopting 
it in toto at present: should it, however, upon an impartial 
and thorough investigation, come forth from the furnace 
as gold, and be found to correspond with the actual state 
of things in nature, my objections, which rest only upon 
some parts of his arrangement of Annulosa, would soon 
vanish. Some of those objections I will state here, and 
some will come in better when I treat of the Systems 
of Entomology. My first objection is, that his Ameta- 
bola, Mandibulata, and Haustellata, approach much 
nearer to each other than they do to the other two classes 
of his circle, or than even these last to each other ; so 
that under this view it should primarily consist of three 
greater groups, resolvable, it may be, into five smaller 
ones. My next objection is, that he has also considered 

a Her. Entomolog. 348. * Ibid. 354. <= Ibid. 373. 

d Ibid. 381. e Ibid> 389i 



DEFINITION OF THE TERM INSECT. 21 

the Trachean and Pulmonary Arachnida as forming one 
class. Whether an animal breathes by gills or tracheae, 
or has a circulation or not, is surely as strong a reason 
for considering those so distinguished as belonging to dif- 
ferent classes, as the taking of their food by suction or by 
manducation is, for separating others to the full as much 
or more nearly related as to their external structure. 
But of this more hereafter. I cannot help, as a last ob- 
jection, lamenting that our learned author has rejected 
from his system a term consecrated from the most remote 
antiquity, and which, even admitting his arrangement, 
might have been substituted for Annulosa, a name bor- 
rowed by Scaliger from Albertus Magnus, neither of 
whom, in Entomology, is an authority to weigh against 
Aristotle, from whom we derive the term Insecta, in 
Greek Evropct. 

As Fabricius did not alter Linne's class Insecta, but 
merely broke up his orders into new ones, which he 
named classes, I shall give you a detail of the alterations 
he introduced into the science in a future letter. 

Having stated what my predecessors have done in 
classification, I shall next proceed to lay before you my 
own sentiments as to-^-What is an insect. Since our 
correspondence commenced, the Arachnida, principally 
on account of their internal organization, have been ex- 
cluded from bearing that name, carrying with them, as 
we have seen, several tribes, which as yet have not 
been discovered to differ materially in that respect from 
the present Insecta : for the sake, therefore, of conve- 
nience and consistencjr, that I may, as far as the case 
will admit, adhere to the Horatian maxim 

Servetur ad imum 

Qualis ab incepto proeesserit et sibi constet, 



22 DEFINITION OF THE TERM INSECT. 

I shall regard as Insects all those Annulosa that respire 
by tracheal and have no circulation, considering the 
Trachean Arachnida and the Myriapoda for the present 
as sub-classes, the one bordering upon the Arachnida, and 
the other upon the Crustacea. Some of these I am ready 
to own seem separated by an interval sufficiently wide 
from the Hexapods, which may be regarded as more pe- 
culiarly entitled to the denomination of Insects. The 
most striking differences will be found in the coalition of 
the head with the trunk in some (Phalangidcs), and the 
disappearance of the annulose form of the body in others 
(Acarus L.), so that the legs only are jointed". Yet an 

a There is some reason for thinking, though the octopod and my- 
riapod insects breathe by trachea?, that there is no small difference in 
thw distribution of these organs. The Trachean Arachnida have only 
a pair of spiracles, from which the tracheae must radiate, if I may so 
apply the term, in order to convey the necessary supply of air to every 
part of the body. Scutigera, as far as I can discover, has only a single 
series of dorsal spiracles (see Plate XXIX.Fig. 20) — an unusual situ- 
ation for them : in these also, to attain the above end, each trachea 
must also radiate, so as to supply each part of the segment it is in. 
Those of lulus, according to the observations of Savi ( Osservaz. per 
servire alia Storia di una Specie de lulus, &c. 15 — ), consist of bundles 
of parallel tracheae. Perhaps these circumstances would warrant the 
considering of these Arachnida and the Myriapoda as primary classes? 
The genus Galeodes is said to breathe by gills similar to those of the 
AraneidcB, which structure, probably, carries with it a system of cir- 
culation, and exhibits a third type in the Arachnida,with four palpi, 
six legs, and a distinct thorax. This genus, then, is the corresponding 
point in the Arachnida to the Hexapod Aptera, as the Scorpions are 
to the CheliferidcE or Pseudo-Scorpions, and the Araneidce, to the other 
Octopods ; and these analogies furnish a strong proof, that the Tra« 
cheans belong rather to Insecta than Arachnida. Comp. N. Diet. 
d'Hist. Nat. xxvi. 445 ; and Desertion de six Arachnid, nouv. &c, 
par Leon Dufour, 16. 

b Mr. MacLeay observes with regard to the Tardigrade, de- 
scribed by Spallanzani and Dutrochet, that " it proves that an animal 
may exist without antennae or distinct annular segments to the body, 
but having two eyes and six articulate legs." (Hor. Entomolog. 350—.) 
Many Acari prove the same thing, De Gfeer, vii. t. vii,/. 14. 



DEFINITION OF THE TERM INSECT. 23 

approach to such structure may be traced in some Hexa- 
pods ; for instance, the coalition of the head and trunk 
in Melophagus, Latr., and that of the trunk and abdomen 
in Sminthurus, Latr. a The Myriapoda exhibit other re- 
markable diiferences ; though their head and trunk are 
distinct, the former antenniferous, and their body annu-< 
lose, the abdomen as well as the trunk is furnished with 
legs, sometimes amounting to hundreds ; but even to this 
a tendency has been observed in some Hexapods b . If 
you examine a specimen of Machilis polypoda, an insect 
related to the common sugar-louse (Lepisma saccharina)* 
you will find that the abdomen is furnished with a double 
series of elastic appendages, which, being instruments of 
motion, may be regarded as representing legs. It is 
worthy of notice, that the Myriapoda when first disclosed 
from the egg have never more than six legs c , and keep 
acquiring additional pairs of them and additional seg- 
ments to their abdomen as they change their skins : and 
it is equally remarkable, that many Hexapods are subject 
to a law in some degree the very reverse of this, having 
many abdominal legs in their first state, and losing them 
all in their last. The union of the head with the trunk 
in the Trachean Arachnida has been regarded as almost 
an unanswerable argument, in spite of their different in- 
ternal organization, for including them in the same class 
with the Pidmonary Arachnida ; but the case of Galeodes, 
which, though furnished with gills, (as an eminent Rus- 
sian Entomologist Dr. G. Fischer is reported to have 
discovered,) implying also a circulation, and evidently 
belonging to the last-mentioned class, has nevertheless a 
distinct thorax consisting of more than one piece, to which 

a De Geer, vii. t. iii./. 8. b Hor. Entomolog. 35' 

c De Geer, Ibid. 571, 583. t. xxxvi./, 20, 21. 



24 DEFINITION OF THE TERM INSECT. 

are affixed only six legs 8 , proves that even this circum- 
stance possesses no weight when set against the organi- 
zation. If it was a difference in this respect, that proved 
the Crustacea classically distinct from Insecta — that like- 
wise was the principal reason for the separation also of 
the Arachnida — it seems to follow that it ought also to 
furnish an argument equally cogent for considering the 
Trachean Arachnida, as well as the Myriapoda, distinct 
from the Pulmonary. 

Another difference between the tribes in question is 
that of their metamorphosis ; and this appears to have 
had great weight with Lamarck, inducing him to include 
in his Arachnida, not only the Tracheans and Myriapods, 
but even the apterous Hexapods, except Pidex, or the 
Anoplura and Thysanura of modern authors- But the 
metamorphosis alone, unless supported by the internal 
organization, will I think scarcely be deemed a sufficient 
reason for separating from each other tribes agreeing in 
that respect, and placing them with others with which 
they disagree. The metamorphosis in some of the Hexr 
apods (Lepidoptera) consists in the loss of legs, the ac- 
quisition of wings, a great change in the oral organs and 
in the general form; in others (some Coleoptera), in the 
acquisition only of wings and a change of shape, the oral 
organs remaining much the same; in others again (Cur- 
cidio L.), in the acquisition of six legs and wings and a 
change of form ; in the flea, in the acquisition of six 
legs and a change of form only ; in the Qrthoptera, He- 
miptera, &c. in the mere acquisition of wings ; . in the 
Libellulidce, in the loss of the mask that covers the mouth 
and the acquisition of wings ; in the Diptera, in the ao- 

* Dufour ubi supra. Hor. Entoniolos. 382, 



DEFINITION OF THE TERM INSECT. 25 

quisition of six legs, wings, a change of the oral organs 
and of the form ; in some of the Octopods (Acarus L.), 
in the acquisition of a pair of legs ; and in others (Pha- 
langium and Aranea L.), solely in a modification of them 
as to their proportions ; in the Myriapods, the alteration 
that takes place in this respect is considerable ; a large 
number of pairs of legs is acquired and many additional 
abdominal segments, and the proportion which the ab- 
domen bears to the whole insect is quite altered. In all 
these cases there is a change more or less, either partial 
or general, of the original shape or organs of the animal; 
and with regard to their metamorphosis, there is a greater 
difference between a young and adult lulus than between 
a young and adult grasshopper or bug: so that if the meta- 
morphosis, per se, be assumed as a principal regulator of 
the class, the grasshopper or bug have as little claim to 
belong to it as the lulus. 

M. Lamarck lays considerable stress upon another 
character — That Insecta engender only once in the course 
of their lives, and Arachnida more than once. But this, 
if examined, will be found to be confined chiefly to the 
Pulmonary Arachnida, the Tracheans following the law 
of Insecta in this respect a . 

You may perhaps object that the bringing of the Tra- 
chean Arachnida and the Myriapoda into the class In- 
secta will render the approximation of them to a natural 
arrangement more difficult, since it will be impossible 
at the same time to connect the Myriapods with the 
Crustacea, and the Trachean with the genuine Arachnida. 

a Male Insecta in some instances engender more than once. Mr. 
MacLeay sen. has observed this with regard to Chrysomela Polygoni, 
and I have noticed it in Bomhyx Mori 



26 DEFINITION OF THE TERM INSECT. 

I admit the validity of your objection, but by no arrange- 
ment of insects in a simple series can we attain this object : 
the difficulty, however, may perhaps be obviated in this 
way. The distribution of organized matter, to adopt 
Mr. Wm. MacLeay's metaphor a , begins in a dichotomy, 
constituting the animal and vegetable branches of the 
great tree of nature, and from these two great branches, by 
means of infinite ramifications, the whole system is form- 
ed, and, what is remarkable, these branches unite again 
so as to represent a series returning into itself, a disco- 
very due to the patient investigation and acumen of our 
learned friend just mentioned. Now, in considering 
the Aptera order, we find at first setting out from the 
Hexapods, a dichotomy, where the Anqplura Leach 
branch off on the one side, and the Thysanura Latr. on 
the other — the former, by means of the Pediculidce, tak- 
ing their food by suction, particularly Phthirus Leach, 
or the Morpion (in which the segments of the trunk and 
abdomen become indistinct 5 ) approach the Octopods by 
the hexapod Ac art L. — the latter by Machilis polypoda 
tending towards the Myriapods. In the Octopod branch 
a further dichotomy takes place, from which you proceed 
on one side to the Araneidce in the Arachnida, by Pha- 
langium, &c. ; and in the other by Chelifer, &c. to Scorpio. 
Again, the Myriapod branch also divides, going by the 
Iulidce to one branch of the Isopod Crustacea, and by the 
Scolopendrida to another. 

But there is another view of this subject before alluded 
to, which may be repeated here, and which seems to 

a Hor. Entomolog. 134. 200. 

b Zoolog. Miscell, iii. t. 146. In this figure the segments are 
made much more distinct than they are in my specimen. 



DEFINITION OF THE TERM INSECT. 27 

prove that the types of form in one natural group or 
class are reproduced in another; this appears to result 
from the following parallel series : 

Ncuropterous Aptera. Arachnida. Crustacea. 

Larva;. 
Psocus Hexapoda Galeodes Larunda. 

Myrmeleon Phalangium. . . . Aranea.... < , " 

Octopoda fDecapoda ma- 

Panorpa i Chchfer Scorpio < , . „ 

1 J J tassma bcorpio 

v- especially. 
Ephemera Myriapoda ##### Isopoda. 

No type representing the Myriapoda has yet been 
discovered in the Arachnida class; but I have little 
doubt of its existence. You will observe that the ana- 
logies between the larvae of the winged orders and the 
Aptera were first noticed by Mr. W. MacLeay a . It is 
probable that these parallel series of representatives of 
each other might be increased, as well as the numbers in 
the respective columns. 

What I have said will, I trust, sufficiently justify me 
for making at present no more material alterations in the 
classification I long since proposed to you b ; I shall, 
therefore, now proceed to define the objects I consider as 
Jnsecta; but I shall first observe — that as Latreille con- 
siders the branchiopod Crustacea or Entomostraca of 
Miiller as entitled to the denomination of Crustaceo- 
Arachnida c ; so his Trachean Arachnida might be called 
Arachnido-Insecta, and his Myriapoda, Crustaceo-Insecta. 

a Hot. Entomolog. 422—. 

b See above, Vol. I. 4th Ed. p. 66. Note \ 

c Surely the denomination ought to have been Arachnido-Crustacea, 
since the learned author considers them as belonging to the Crustacea 
class, . 



28 DEFINITION OF THE TERM INSECT. 

Sub-kingdom — Annulosa a . 
Class — Insecta. 
First Definition — From their external Organization. 
Body — divided into Head-^-Trunk— Abdomen. 

Head. — Principal seat of the organs of sensation. 

Organs of sight. Immoveable eyes, simple or com- 
pound, varying in number. 

Organs of hearing uncertain, probably connected 
with the antennae. 

Organ of taste. Ligula or palate within the mouth, 
accompanied by the organs of manducation — a pair 
of mandibles and maxillae and an upper and lower 
lip, or their representatives. 

Organs of touch. Principally two jointed antennas 
or their representatives, and four jointed feelers — 
two maxillary and two labial. 

Trunk. Principal seat of the organs of motion. 
Organs of walking, runnings or jumping. Six or 

eight jointed thoracic legs, in pairs. 
Organs of fight. Four wings or their representa- 

a It may not be without use to give here a short definition of the 
Annulosa ; I mean excluding the Vermes, which Mr. W. MacLeay 
has included ; and the Annelida, which Latreille has made the fifth 
of his Annulose classes. Ann. du Mus. 1821. 

Annulosa. Animal invertebrate, oviparous ; external integument of 
a firmer consistence than the internal substance, serving 
as a general point of attachment to the muscles ; ci/es 
immoveable ; legs more than four, jointed. 
Classes. 

1. Crustacea. Gills external ; more than eight legs. 

2. Arachnida. Gills internal ; spiracles ; eight legs. 

3. Insecta. Tracheae; spiracles; six to eight thoracic legs. 



DEFINITION OF THE TERM INSECT. 29 

tives, mostly with branching nervures containing 
air-vessels ; found in the majority of the class. 
Oigans [external) of respiration. A double set of 
lateral spiracles, some for expiration. 

Abdomen. Principal seat of the organs of generation. 

Organs of motion. In the Myriapods many pairs 
of acquired legs ; in the Thysanura elastic ventral 
or caudal appendages. 

Organs of respiration. A double series of lateral 
spiracles for inspiration in the majority : in some 
only a single series, and in others only a single 
pair. 

Organs of gerieration those common to the Ver- 
tebrata, but retractile within the body, attended 
usually by various anal appendages, particularly 
a forceps in the males, and an ovipositor in the 
females. 

Second Definition — From their internal Organization. 

Sensation. 

Nervous System. A small brain usually subbiiobed, 
crowning a knotty double medullary chord ; nerves 
proceeding from the brain and other ganglions to 
all parts of the body. 
Circulation. 

Heart replaced by a simple alternately contracting 
dorsal vessel or pseudocordia, without arteries or 
veins, but filled with a white cold sanies. 
Respiration. 

Lungs replaced by tracheae, which receive the air 
from the spiracles, and distribute it by bronchia? 
infinitely ramified. 



30 DEFINITION OF THE TERM INSECT. 

Digestion. 

Liver and biliary vessels in most replaced by from 
2 to 4- 150 floating hepatic filaments opening into 
the space between the two skins of the intestinal 
canal below the pylorus. 
Generation. 

Internal organs-. Males — Vasa deferentia, and vesi- 
culae seminales, and the other ordinary organs. Fe- 
males — Ovary usually bipartite, with palmate lobes; 
genital organs single and mostly anal ; one sexual 
union impregnates the female for her life. 
Development. In their passage to their adult state, 
after they have left the egg, insects undergo several si- 
multaneous changes of their integument or successive 
moults, and the majority assume three distinct forms, 
with distinct organs, which appear as rudiments in their 
second state, and are completely developed in their last. 

In defining the Aracknida I shall only mention those 
particulars in which they differ from Insectce in their ex- 
ternal anatomy. 

Class — Arachnida. 
Body. 

Head and Trunk usually not separated by a suture. 
Eyes. Two to eight, not lateral. 
Mandibles cheiiform or unguiculate, representing 
the interior pair of the antennae of the Crustacea. 
Palpi pediform or cheiiform. 

Trunk. Legs eight or their representatives : tibiae 
mostly consisting of two joints. 
Abdomen with from two to eight spiracles. 



definition of the term insect. 31 

Sensation. 

Nervous System. A small bilobed brain crowning a 
double, knotty, medullary chord; nerves proceeding 
from the brain and other ganglions to all parts of 
the body. 
Circulation. 

Heart unilocular, inaurite, with a system of circulation 
by arteries and veins ; blood a cold white sanies. 
Respiration. 

Lungs replaced by internal gills receiving the air by 
spiracles. 
Digestion. 

Live?-, consisting of conglomerate glands, and enve- 
loping the intestines a ; hepatic ducts. 
Generation. 

Genital organs double, ventral ; more than one sexual 

union in the course of life. 
The external characters in this class are the same al- 
most in every respect as those which distinguish the 
Phala?igida?, the whole difference consisting almost in 
the systems of circulation, respiration, and digestion. 
Perhaps some future anatomist may discover in the tribe 
just mentioned, that there is a nearer agreement between 
them and the Arachnida in these systems than is at pre- 
sent suspected, which would prove them true Arachnida. 
I am inclined to think that Phrynus and Gonyleptes, &c. 
breathe by branchial spiracles; but having no opportu- 

a What L. Dufour regards a3 the liver in Scorpio (N. Diet. d'Hist. 
Nat. xxx. 421.) Treviranus looks upon as an Epiploon (Fettkorper) 
both in Scorpio and Aranea. 6. t. If. 6. A A. t. ii./. 24. dd. Hepatic 
ducts: t. If. 6. ii. t. ii./. 24. /3. /3. /3. /3. 



32 DEFINITION OF THE TERM INSECT. 

tunity of examining living specimens, I dare not speak 
with any confidence on the subject. 

Having thus given you a view of the most important 
diagnostics by which what we have all along called In- 
sects may scientifically be distinguished from other inver- 
tebrate animals, it may not be without use, if, under 
this head, I take a more popular and familiar view of 
die subject, and say something upon those distinctions 
which may attract the attention of the more common 
observer. 

The notion of diminutive size, particularly as com- 
pared with vertebrate animals, seems more frequently 
attached to the idea of an insect than any other ; and 
this notion is generally correct, for one insect that is 
bigger than the least of the above animals, thousands 
and thousands are vastly smaller : but there exist some 
that are considerably larger, whether we take length or 
bulk into consideration, and this in almost every order. 
To prove this most effectually, and that you may have a 
synoptical view of the comparative size of the larger 
insects of the different orders and tribes, I now lay be- 
fore you a table of the dimensions of such of the largest 
as I have had an opportunity of measuring, including 
particularly those giants that are natives of the British 
isles. 



DEFINITION OF THE TERM INSECT. 



33 






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VOL, III. 



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DEFINITION OF THE TERM INSECT. 



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DEFINITION OF THE TERM INSECT. 



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DEFINITION OF THE TERM INSECT. 



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38 DEFINITION OF THE TERM INSECT. 

From this table you see that several insects included 
in it exceed some of the smallest Vertebrata in bulk. In 
the Mammalia, the Sorex Araneus, called by the common 
people here the Ranny, is not more than two inches 
long excluding the tail ; and the Mus messorius, or har- 
vest-mouse, peculiar to the southern counties of England, 
is still more diminutive : so that to these little animals, 
the larger Dynastidce, Goliathi, and Prioni, &c, appear 
giants, and may compete with the mole in size. Even some 
of the beetles of our own country, as the great Hydrophi- 
lus, the stag-beetle, &c, are more bulky than the two 
first-named quadrupeds. Amongst the birds, many Piece, 
Passeres, &c, yield to several insects in dimensions, and 
their wings when expanded do not extend so far as those 
of not a few Lepidoptera. The great owl-moth of Brazil 
{Erebus Strix) in this respect is a larger fowl than the 
quail. Those beautiful little creatures, the humming- 
birds (Trochilus L.), the peculiar ornament and life of 
tropical gardens, which emulate the most splendid but- 
terflies in the brilliancy of their plumage, are smaller 
than a considerable number of insects in almost every 
order, and even than some of those that are natives of 
Britain. Various reptiles also are much inferior in size 
to many of the insects of the above table. The smallest 
lizard of this country would be outweighed by the great 
British beetles lately mentioned, and the mole-cricket 
{Gryllotalpa vulgaris); and some of the serpent tribe are 
smaller than the larger Scolopend?*a and Iuli. Amongst 
thejishes also, though some are so enormous in bulk, 
others in this respect yield the palm to several insects. 
The minnow and the stickleback that frequent our own 
pools and streams are considerably inferior in size to 
some of our water beetles. 



DEFINITION OF THE TERM INSECT. 39 

111 looking over the table, and comparing the different 
species that compose it with each other, you will perceive 
that the largest insects of the two sections of Hemiptera, 
of the Lepidoptera as to their body merely, of the Hy- 
menopter-a and Diptera, in general size fall considerably 
short of those of the other orders ; and that certain indi- 
viduals of the Orthoptera and Aptera bear away the 
palm in this respect from all the rest In the Coleoptera 
the giants, with the exception of the Goliathi, are chiefly 
to be found amongst the timber devourers in the Lamel- 
licorn and Capricorn tribes. Of orthopterous insects the 
Phasmidce present the most striking examples of magni- 
tude : and in the Neuroptera, the Agrionidce of great 
length. 

It is worthy of remark here, that although the tropical 
species of a genus usually exceed those of colder climates 
in size, the Gryllotalpa of Brazil is very considerably 
smaller than that of Europe: whether this is the case 
with the rest of the cricket tribe I have not had an op- 
portunity of ascertaining. The Lepidoptera, though often 
remarkable for the vast expansion of their " sail-broad 
vans," if you consider only their bodies, never attain to 
gigantic bulk. Even the hawk-moths [Sphinx L.), though 
usually very robust, make no approach to the size of 
the great beetles, or the length of some of the spectres 
(Phasma) and dragon-flies (Agrionidce). With regard 
to the superficial contents of their wings, a considerable 
difference obtains in different species where they expand 
to the same length — for the secondary wings are some- 
times smaller than the primary, and sometimes they equal 
them in size. In some instances, also, the latter although 
long are narrow, and in others they are nearly as wide 
as long : regard, therefore, should be had to their ex- 



tO DEFINITION OF THE TERM INSECT. 

pansion both ways. In the Hymenoptera and Diptera, 
the principal giants are to be found in the predaceous or 
blood-sucking tribes, as Scolia, the Sphecida, PompilidcE, 
Vespidce, &c, belonging to the former order; and the 
Asilidce and Tabanidce to the latter. The true and false 
humble bees [Bombus and Xylocopa) and the fly tribe 
(Muscidte), though they sometimes attain to considerable 
size, scarcely afford an exception to this observation. 
Amongst the Aptera none of the Hexapods strike us by 
their magnitude, and few of the Octopods, though the 
legs of some of the Phalangidce inclose a vast area. That 
in the table would with them describe a circle of six 
inches diameter, though its body is little more than a 
quarter of an inch in length. The Myriapods exceed 
most insects in the vast elongation of their body, which 
with their motion gives them no slight resemblance to 
the serpents. In the class Arachnid^ the bird-spiders 
{My gale) are amongst the principal giants, nor do the 
Scorpions fall far short of them — both of them when alive 
often alarming the beholder as much by their size as bv 
their aspect. 

But as I have before observed, generally speaking, one 
of the most remarkable characters of the insect world, is 
the little space they occupy ; for though they touch the 
vertebrate animals and even quadrupeds by their giants, 
yet more commonly in this feature they go the contrary 
way, and by their smallest species reach the confines of 
those microscopic tribes that are at the bottom of the 
scale of animal life. I possess an undescribed beetle, 
allied to Silpka minutissima E. B.% which, though fur- 

a S. minutissima of Marsham is synonymous with Dermestes ato- 
marius De Geer, Scaphidium atomarium Gyllenh., and Latridius fasci- 
pularis Herbst, but surely arranging with none of these genera, being 



DEFINITION OF THE TERM INSECT. 41 

nished with elytra, wings, antennae, legs, and every other 
organ usually found in the order it belongs to, is abso- 
lutely not bigger than the full stop that closes this period. 
In several other coleopterous genera there are also very 
minute species, as in Cryptophagus, Anisotoma, Agaihidi- 
um, &c. I know no orthopterous insect that can be called 
extremely minute, except that remarkable one found on 
the Continent in the nests of ants, the Blatta Acervorum 
of Panzer", but now called, I believe, Myrmecophilus : 
nor indeed any in the Hemiptera, Neuroptera, and Di- 
piera.) that approach the extreme limits of visibility : bat 
in the Lepidoptera, the pygmy Tinea occultella is almost 
invisible except in flight, being scarcely thicker than 
a horse's hair, and proportionably short ; indeed, many 
others of those lovely Lilliputians, the subcutaneous Tinece, 
decorated with bands of gold and silver, and studded 
with gems and pearls, that in larger species would dazzle 
the beholder's eye, are in size not much more conspicu- 
ous. In the Hymenoptera order, Ichneumon Punctum of 
Dr. Shaw, which forms so striking a contrast to his giant 
Phasma dilatatum, being placed together in the same 
plate; and another that I possess, under the trivial name 
of Atomos, would elude the searching eye of the ento- 
mologist unless when moving upon glass. Linne named 
the tribe of parasites to which these belong, Minuti, 
on account of their generally diminutive size. But 
these little minims, under the superintendence of Pro- 
vidence, are amongst the greatest benefactors of the 

sufficiently distinguished from them and every other insect by its 
singular capillary wings. In my cabinet it stands under the name of 
Trichopteryx K. 

a Panz. Fn. Germ. Init. Ixii. 24. Comp. Hor. Entomolog. Addenda, 
&c. 523. 



42 DEFINITION OF THE TERM INSECT. 

human race, since they keep within due bounds the va- 
rious destroyers of our produce. 

The number of minute species of insects seems greatly 
to exceed that.of large ones, at least in Europe, of which 
it may be asserted probably with truth, that two-thirds 
are under a quarter of an inch in length, and one-third 
not exceeding much a duodecimal of it. It might hold 
good perhaps in Coleoptera, Hymenoptera, Diptera, and 
Aptera : but in Qrthoptera, Hemiptera, Neuroptera, and 
especially Lepidoptcra, a large proportion would be found 
to exceed three lines in length. Neither can it be af- 
firmed of extra-European species, of those at least pre- 
served in cabinets, amongst which it is rare to find an 
insect less than the fourth of an inch long. This, how- 
ever, must probably be attributed to the inattention of 
collectors, who neglect the more minute species. 

Though size forms a pretty accurate distinction between 
insects and the great bulk ofcvertebrate animals, it affords 
less assistance in separating them from the invertebrate 
classes, which are of every size, from the monstrous bulk 
of some Cephalopoda (cuttle-fish) and Mollusca (shell- 
fish, &c.) to the invisible infusory animalcule i but ex- 
ternal characters, abundantly sufficient for this purpose, 
may be drawn from the general covering, substance, form, 
parts, and organs of the body. As I shall enter into pretty 
full details upon this subject when I come to treat of the 
external anatomy of insects, I shall here, therefore, only 
give such a slight and general sketch of the distinctions 
just mentioned, as will answer the end I have in view. I 
must here repeat what I have before observed, and what it 
is necessary that you should always bear in mind, namely, 



DEFINITION OF THE TERM INSECT. 43 

that at the limits of classes and of every other natural 
group, the characters begin to change, those peculiar to 
the one group beginning gradually to disappear, and 
those of the other to show themselves; so that it is im- 
possible almost to draw up a set of characters so precise 
as exactly in every respect to suit all the members of any 
natural group. 

Whichever way we turn our eyes on the objects of 
creation, above — below — athwart, analogies meet us in 
every direction, and it appears clear, that the Book of 
Nature is a Book of Symbols, in which one thing repre- 
sents another in endless alternation. And not only does 
one animal, &c. symbolize another, but even between the 
parts and organs of one set of animals there is often an 
analogy as to their situation and use, when there is little 
or no affinity as to their structure — or again, the analogy 
is in their situation, without affinity in either structure 
or use. Thus certain parts in one tribe represent other 
certain parts of another tribe, though as to their structure 
there is often a striking disagreement. This is particu- 
larly observable between the vertebrate and invertebrate 
animals. I shall therefore, in my remarks on the ge- 
neral and particular structure of insects, contrast it in its 
most important points with that of the first-mentioned 
tribe. 

The first thing that strikes us when we look at an 
insect is its outside covering, or the case that incloses its 
muscles and internal organs. If we examine it attentively, 
we find that it is not like the skin of quadrupeds and 
other Vertebrata, covering the whole external surface of 
the body ; but that in the large majority it consists of 
several pieces or joints, in this respect resembling the 



44 DEFINITION OF THE TERM INSECT. 

skeleton of the animals just named; and that even in those 
in which the body appears to have no such segments, as 
in many of the Mites (Acarus L.), they are to be found in 
the limbs. This last circumstance, to have externally 
jointed legs, is the peculiar and most general distinction by 
which the Insecta of Linne, including the Crustacea, may 
always be known from the other invertebrate animals a . 

If we proceed further to examine the substance of this 
crust or covering, though varying in hardness, we shall 
find it in most cases, if we exclude from our considera- 
tion the shells of the Mollusca, &c, better calculated to 
resist pressure than that of the majority of animals that 
have no spine. In all the invertebrate tribes, indeed, the 
muscles, there being no internal skeleton, are attached 
to this skin or its processes, which of course is firmer 
than the internal substance; but in insects it is very often 
rigid and horny, and partially difficult to perforate, sel- 
dom exhibiting that softness and flexibility which is found 
in the cuticle of birds and most quadrupeds. From this 
conformation it has been sometimes said, that insects 
carry their bones on the outside of their body, or have 
an external skeleton. This idea, though not correct in 
all respects, is strictly so in this — that it affords a general 
point of support to the muscles, and the whole structure 
is erected upon it, or rather I should say within it. The 
difference here between Insects and the Vertebrata seems 
very wide; but some of the latter make an approach to- 
wards it. I allude to the Chelonian Reptiles ( Testudo L.), 

a The Annelida have, however, sometimes jointed organs, which 
facilitate their progressive motion whether vermicular or undulatory ; 
but they cannot be deemed legs, since they neither support the body 
nor enable it to walk, &e. Latreille Anim. invertebr. Artie. 126. Ann. 
du Mus. 1821. 



DEFINITION OP THE TERM INSECT. 45 

in which the vertebral column becomes external or merges 
in the upper shell. The cyclostomous fishes also are not 
very wide of insects as to their integument. But on this 
subject I shall be more full hereafter. 

The forms of insects are so infinitely diversified that 
they almost distance our powers of conception : in this re- 
spect they seem to exceed the fishes and other inhabitants 
of the ocean, so that endless diversity may be regarded 
as one of their distinctions. But on all their variations 
of form the Creator has set his seal of symmetry ; so that, 
if we meet with an animal in the lower orders in which 
the parts are not symmetrical, we may conclude in general 
that it is no insect. 

But it is by their parts and organs that insects may be 
most readily distinguished. In the vertebrate animals, 
the body is usually considered as divided into head, 
trunk, and limbs, the abdomen forming no part of the 
skeleton ; but in the insect tribes, besides the organs of 
sense and motion, the body consists of three principal 
parts — Head, Trunk, and Abdomen — the first, as was 
before observed, bearing the principal organs of sense 
and manducation ; the second most commonly those of 
motion ; and the third those of generation — the organs of 
respiration being usually common to both trunk and ab- 
domen. These three primary parts, — though in some in- 
sects the head is not separated from the trunk by any 
suture, as for instance in the Arachnid a ,• and in others, 
head, trunk, and abdomen form only one piece, as in some 
mites, — still exist in all, and in the great majority they are 
separated by incisures more or less deeply marked : this 
is particularly visible in the Hymenoptera and Diptera, 
which, in this respect, are formed upon a common model ; 



46 DEFINITION OF THE TERM INSECT. 

and in the rest, with the above exceptions, it may be 
distinctly traced. 

The head of insects is clearly analogous to that of 
vertebrate animals, except in one respect, that they do 
not breathe by it. It is the seat probably of the same 
senses as seeing, hearing, smelling, tasting — and more pe- 
culiarly perhaps of that of touch. The eyes of insects, 
though allowed on all hands to be organs of sight, are 
differently circumstanced in many particulars from those 
of the animals last mentioned ; they are fixed, have nei- 
ther iris nor pupil, are often compound, and are without 
eyelids to cover them during sleep or repose ; there are 
usually two compound ones composed of hexagonal 
facets, but in some instances there are four ; and from 
one to three simple in particular orders. The antenna? 
of insects in number and in situation correspond with the 
ears of the animals we are comparing with them ; but 
whether they convey the vibrations of sound has not 
been ascertained : that they receive pulses of some kind 
from the atmosphere I shall prove to you hereafter — so 
that if insects do not hear with them in one sense, they 
may, by communicating information, and by aeroscopy, to 
use Lehman's term, not directly in his sense 3 , supply the 
place of ears, which would render them properly ana- 
logous to those organs. That in numbers these remark- 
able organs are tactors is generally agreed, but this is not 
their universal use. That insects smell has been often . 
proved ; but the organ of this sense has not been ascer- 
tained. What has improperly been called the clypeus, 
or the part terminating the face above the upper lip 
{labrum), is in the situation of the nose of the Vertebrata, 

a Be Antennis Insect, ii. 65. 



DEFINITION OF THE TERM INSECT. 47 

and therefore so far analogous to it, and in some cases 
even in form : I therefore call it the nose. Whether this 
part represents the nose by being furnished with what 
answer the purpose of nostrils, residing somewhere at 
or above the suture that joins it to the upper lip, I cannot 
positively affirm; but from the observations of M. P. 
Huber, with regard to the hive-bee, it appears that at 
least these insects have the organ of the sense in question 
somewhere in the vicinity of the mouth, and above the 
tongue a : analogy, therefore, would lead us to look for 
its site somewhere between the apex of the nose and the 
upper lip ; and in some other cases, which I shall here- 
after advert to, there is further reason for thinking that 
it actually resides at the apex of the nose. The organ of 
taste in insects, though some have advanced their palpi 
to that honour, is doubtless in some part within the 
mouth analogous in a degree to the tongue and palate of 
the higher animals. The organs of manducation, in 
what may be deemed the most perfect description of 
mouth, consist of an upper lip closing the mouth above, 
a pair of mandibles moving horizontally that close its 
upper sides, and a lower lip with a pair of maxillce at- 
tached to it, which close the mouth below and on the 
under sides, both labium and maxillae being furnished 
with jointed moveable organs peculiar to annulose pedate 
animals, called palpi. In some tribes these organs as- 
sume a different form, that they may serve for suction ; 
but though in many cases some receive an increment at 

a Nouv. 06s. sur les Abeilles, ii. 376 — . It appears from 1VL Huber's 
experiment, that it was only when the hair-pencil, impregnated with 
the oil of turpentine, was presented " pres de la cavite, an dessus 
de Vinsertion de la trompe," that the bee was sensible of the odour. 



48 DEFINITION OF THE TERM INSECT. 

the expense of others, and a variation in form takes place, 
none, as M. Savigny has elaborately proved, are totally 
obliterated or without some representative 11 . The organs 
now described, except the upper lip, are formed after 
a quite different type from those of Vertebrata, with which 
they agree only in their oral situation and use. 

The second portion of the body is the Trunk, which 
is interposed between the head and abdomen, and in 
most insects consists of three principal segments, sub- 
divided into several pieces, which I shall afterwards ex- 
plain to you. I shall only observe, that some slight ana- 
logy may perhaps be traced between these pieces and the 
vertebrae and ribs of vertebrate animals, particularly the 
Chelonian reptiles. This is most observable in Gryllus L. 
and Libellula L., in which the lateral pieces of the trunk 
are parallel to each other 5 . In the Dijptera and many 
of the Aptera most of these pieces are not separated by 
sutures. Each of the segments into which the trunk is 
resolvable bears a pair of jointed legs, the first pair point- 
ing to the head, and the two last to the anus. These le«-s 
in their composition bear a considerable analogy to those 
of quadrupeds, &c, consisting of hip, thigh, leg, and 
foot ; but the last of these, the foot or Tarsus, is almost 
universally monodactyle, unless we regard the Calcaria 
that arm the end of the tibia, as representing fingers or 
toes, an idea which their use seems to justify. Acheta 
monstrosa and Tridactylus paradoxus, however c , exhibit 
some appearance of a phalanx of these organs. They 
differ from them first in number, the thoracic legs beino- 

% Anim. sans Vertebr. I. i. Mem. i. 

b Plate VIII. Fig. 10—14; IX. Fig. 6—8. 

c Coquebert Illust. Ic. iii. /. xxi.f. 3. 



DEFINITION OF THE TERM INSECT. 49 

invariably six in all insects, with the exception of the 
Octopods or most of the Trachean Arac/mida, which have 
usually eight. In the Myriapods, though there are hun- 
dreds of abdominal legs, only six are affixed to the trunk. 
Next they differ with regard to the situation of their legs; 
for though the anterior pair or arms are analogous in 
that respect, the posterior pair are not, since in quadru- 
peds these legs are placed behind, the abdomen, but in 
insects before it — in fact, in the former the legs may be 
considered as placed at each end of the body, excluding 
only the head and tail, but in the latter in the middle. 
Though they correspond with those of quadrupeds in 
being in pairs or opposite to each other, yet their direc- 
tion with respect to the body is different, the legs of 
quadrupeds, &c. being nearly straight, whereas in insects 
they are bent or form an angle, often very obtuse at the 
principal articulations, which occasions them to extend 
far beyond the body, and when long' to inclose a propor- 
tionally greater space. The wings are the organs of 
motion with which the upper side of the trunk is fur- 
nished ; and these, though they are the instruments of 
flight, are in no other respect analogous to those of 
birds, which replace the anterior legs of quadrupeds, lut 
approach nearer, both in substance and situation, to the 
fins of some fishes, and perhaps in some respects even to 
the leaves of plants. M. LatreilJe is of opinion, That 
the four wings or their representatives replace the four 
thoracic legs of the decapod Crustacea*. Upon this 
opinion, which shows great depth of research and prac- 
tical acumen, I shall have occasion to express my senti- 
ments when I come to treat more at large on the anatomy 

8 Hor. Entomolog. 413 — . 
VOL. Til. E 



50 DEFINITION OF THE TERM IXSECT. 

of the trunk and its members ; at any rate they do not 
replace the two anterior pair of legs of the hexapod 
Altera. When merely used as wings, they commonly 
consist of a fine transparent double membrane, strength- 
ened by various longitudinal and transverse nervures, or 
bones as some regard them, accompanied by air-vessels, 
of which more hereafter, as well as of their kind and cha- 
racters. I shall only observe, that insects are known 
from all other winged animals, by having /our wings, or 
what represent them, and this even generally in those 
that are supposed to have only a pair. Another pecu- 
liarity distinguishes the trunk of insects that you will 
in vain look for in the vertebrate animals — these are one 
or two pair of lateral spiracles or breathing pores. Though 
the respiratory sacs, &c. of birds are almost as widely 
dispersed as the tracheae and bronchise of insects 3 , yet 
their respiration is perfectly pulmonary, and nothing like 
these pores is to be discovered in them. 

The principal peculiarity of the third part of the body, 
the abdomen, is its situation behind the posterior pair of 
thoracic legs, and its rank as forming a distinct portion 
of what represents the skeleton. In most insects it is so 
closely affixed to the posterior part of the trunk as to 
appear like a continuation of it, but in the majority of 
the Hymenoptera and Diptera, and in the Araneidan 
Arachnida, or spiders, it is separated by a deep incisure; 
and in the first-mentioned tribe is mostly suspended to 
the trunk by a footstalk, sometimes of wonderful length 
and tenuity. In the Mammalia the male genital organs 
are partly external ; but in insects as well as in many of 
the vertebrate animals, except when employed, they are 
* N, Diet. d'Hist, Nat, xxviii. ; compare 104 and 110. 



DEFINITION OF THE TERM INSECT. 51 

retracted within the body. This part is the principal 
seat of the respiratory pores or spiracles, many having 
eight in each side, while others have only one. 

Such are the principal external characters which di- 
stinguish hisecta and Arachnida, or what we have here- 
tofore regarded as insects, to which here may be added 
another connected with their internal organization. The 
union of the sexes takes place in the same manner as 
amongst larger animals ; and the females with very few 
exceptions, more apparent than real, are oviparous. 
They are, however, distinguished by this remarkable pe- 
culiarity already alluded to, that, except in the case of 
the Arachnida, one impregnation fertilizes all the eggs 
they are destined to produce. In most cases, after these 
are laid, the females die immediately, and the males after 
they have performed their office, though they will some- 
times unite themselves to more than one female. One 
other circumstance may be named here — that no genuine 
insect or Arachnidan has yet been found to inhabit the 
ocean. 

Before I conclude this letter, it is necessary to apprize 
you, that every thing which it contains relative to the 
characters of insects, has reference to them only in their 
last or perfect state, not in those preparatory ones through 
which you are aware that the majority of them must pass. 
The peculiar characteristics of them in these states — in the 
egg, the larva, and the pupa, will be the subjects of my 
next letters, which will be devoted to a more detailed 
view of the metamorphosis of insects than I gave you 
before when adverting to this subject a . 

a See above, Vol.'. J. Ed. 4. p. 63 — - 
E 2 



LETTER XXIX. 



STATES OF INSECTS. 

EGG STATE. 

ON a former occasion I gave you a general idea of what 
has been called, perhaps not improperly, the metamor- 
phosis of insects 3 ; but since that time much novel and 
interesting speculation on the subject has employed the 
pens of many eminent Physiologists ; and besides this, 
the doctrine then advanced of successive developments 
has been altogether denied by a very able Anatomist, 
Dr. Herold, who, with a hand, eye, and pencil, second 
only to those of Lyonnet, has traced the changes that 
gradually take place in the structure of the cabbage-but- 
terfly (Pieris Brassicce) on passing through its several 
states of larva, pupa, and imago. It is necessary, there- 
fore, that previously to considering separately and in 

a The word p£Tcipo(><pou, and its derivative fiirafcoQipaarig, are not 
extant in any Greek writer before the date of the New Testament. 
They are used to express any external change of form or colour, and 
metaphorically an inward change and progressive improvement of the 
mind. Comp. Matth. xvii. 2. Mli&n. Far. Hist. 1. i. c. 1. Rom. xiii. 2. 
2 Cor. hi. 18. They are, therefore, not improperly applied, as some 
have supposed, to the changes of insects. 



STATES OF INSECTS. 53 

detail the states of insects, I should again call your atten- 
tion to this subject, and endeavour to ascertain whether 
Dr. Herold's hypothesis rests upon a solid foundation ; 
or whether that adopted from Swammerdam by all the 
most eminent Entomologists and Physiologists since his 
time can be maintained against it. 

I shall first give you a short abstract of the new hy- 
pothesis. 

According to Dr. Herold — The successive skins of the 
catetpillar, the pupa-case, the future butterfly, and its 
parts and organs, except those of sex which he discovered 
in the newly excluded larva, do not preexist as germes, but 
are formed successively from the rete mucosum, which it- 
self is formed anew upon every change of shin from what 
he denominates the blood, or the chyle after it has passed 
through the pores of the intestinal canal into the general 
cavity of the body, where, being oxygenated by the air- 
vessels, it performs the nutritive functions of blood. He 
attributes these formations to a vis formatrix (Bildende 
Kraft). 

The caul or epiploon (Fett-masse), the corps graisseux 
of Reaumur, fyc, which he supposes to be formed from the 
superfluous blood, he allows, with most physiologists, to be 
stored up in the larva, that in the pupa state it may serve 
for the development of the imago. But he differs from 
them in asserting that in this state it is destined to two 
distinct purposes— first, for the production of the muscles 
of the butterfly, which he affirms are generated from it in 
the shape of slender bundles of fibres ; —and secondly, for 
the development and nutrition of the organs formed in the 
larva, to effect which, he says, it is dissolved again into 
the mass of blood, and being oxygenated by the air-vessels,. 



,54 STATES OF INSECTS. 

becomes Jit for nutrition, whence the epiploon appears to 
be a kind of concrete chyle*. 

Need I repeat to you the hypothesis to which this 
stands opposed— That every caterpillar at its first exclu- 
sion contains within itself the germe of the future butterfly 
and of all its envelopes, which successively presenting them- 
selves are thrown off, till it appear in perfection and 
beauty, with all its parts and organs, when no further de- 
velopment takes place. 

I believe you will agree with me, when you have read 
and considered the above abstract of Dr. Herold's hy- 
pothesis, that in it he substitutes a name for knowledge, 
talks of a visformatrix because his assisted eye cannot 
penetrate to the primordial essence or state of the germes 
of being, and denies the existence of what he cannot dis- 
cover 13 . From ancient ages philosophers have done the 
same, to conceal their own ignorance of causes under a 
sounding name, when they have endeavoured to pene- 
trate within the veil of the sanctum sanctorum, which it 
is not permitted to vain man to enter. This has occa- 
sioned the invention, not only of the term in question, 
but of many others, as little meriting the appellation of 
Signs of ideas ; such as Plastic Nature, Epigenesis, Pan- 
spermia, Idea seminalis, Nisus formativus, &c. But upon 

a Entwickelungsgeschichte der Schmetterlinge 12 — 27. 105 — . 

b Dr. Virey's observations under the article Embryo (iV. Diet. 
d'Hist. Nat, x, 195,) deserve here to be considered. " II y a done 
quelque chose au dessus de l'intelligence humaine dans cette forma- 
tion des etres ; en vain on veut l'approfondir, e'est un abime dans 
lequel on ne voit que la main de Dieu. A quoi bon s'appesantir sur 
le mystere de la formation des etres, sans esperance de l'expliquer ? 
Ne vaut-il pas mieux observer les operations de la nature autant 
qu'il est permis a Pceil humain de les appercevoir?" 



STATES OF INSECTS. 55 

this subject you cannot do better than consult what the 
learned Dr. Barclay has said in his admirable work On 
Life and Organization*, in which he has placed the 
inanity, the vox et 'prcBterea nihil, of such high-sounding 
terms in their true light. The processes of nature in 
the formation and development of the^a^s in utero, of 
the chick in the egg, of the butterfly in the caterpillar, 
we in vain attempt fully to investigate ; yet we can easily 
comprehend that pre-existent germes, by the constant 
accretion of new matter in a proper state, may be gra- 
dually developed, but we find it impossible to conceive 
how, by the action of second causes, without the inter- 
vention of the first cause, the butterfly should be formed 
in the caterpillar, unless it preexists there as a germe or 
foetus. " Is it not clear," asks Dr. Virey in his lively 
manner, " as Blumenbach and other Physiologists main- 
tain, that there is a formative power, a nisas formativus, 
which organizes the embryo ? Admirable discovery ! " 
says he, " which teaches us that the foetus forms itself 
because it forms itself ! As if you should affirm that the 
stone falls because it falls b ! " Had Dr. Herold considered 
what Bonnet says with as much good sense as modesty, 
he would never have imagined that his discovering the 
organs of the butterfly one after the other at certain pe- 
riods in the caterpillar, was any sound argument against 
their preexistence and coexistence as germes. " Or- 
gans," says that amiable and excellent Physiologist, 
" that have no existence as to us, exist as they respect 
the embryo, and perform their essential functions ; the 
term of their becoming visible is that which has been 

* <$ x iv. b N. Diet. d'Hist. Nat. x. 193. 



56 STATES OF INSECTS. 

erroneously mistaken for the period of their existence 3 ." 
This has been Dr. Herald's, grand error; he mistook the 
commencement of the appearance of the organs of the 
butterfly for that of their existence^ and yet the early ap- 
pearance of the sexual organs ought to have led him to 
a conelusion the reverse of that which he has adopted. 

Dr. Virey has observed with great truth — that " Every 
being has a peculiar and unique nature, which would be 
impossible if the body was composed of parts made at 
several intervals, and without a uniform power that acts 
by concert b :" and every Physiologist acquainted with 
the history of insects that undergo a complete metamor- 
phosis will allow, that their developments and acquisition 
of new parts and organs take place according to a law 
which regulates the number, kind, and times of them, 
differing in different species, and which has had an in- 
variable operation, since the first creation, upon every 
sound individual that has been produced into the world. 

In consequence of this law, one species changes its 
skin only four times, and another^*? or six ; — in some 
cases the first skins shall be covered or bristled with 
hairs or spines, and the last be naked and without arms ; 
-—that which forms the case of the pupae shall differ in 
form and substance from the preceding skins, varying in 
both respects in different species; and finally the butterfly 
shall invariably follow, when no other change but the 

a CEuv. v. 279. " II n'est pas exact de dire que le coeur, la tete, et 
la moelle epiniere, sont formes les premiers dans les foetus des ani- 
maux a sang rouge et vertebres," says Dr. Virey; " mais il faut dire 
seulement que tel est l'ordre dans lequel ces organes commencent a 
devenir visibles." N. Diet. d'Hist. Nat, x. 1967 

b Ibid, ID'S. 



STATES OF INSECTS. 57 

last mortal one shall take place. Can this law, so con- 
stantly observed, be the result of a blind power ? Or are 
we to suppose that the Deity himself is always at work 
to create the necessary organs in their time and place? 
Is it not much more consonant to reason and the General 
analogy of nature, to suppose that these parts and organs 
exist in embryo in the newly-hatched caterpillar, and 
grow and are successively developed by the action of the 
nutritive fluid ? In the pupa of many Diptera the in- 
closed animal, even under the microscope, appears with- 
out parts or organs, like a mere pulp ; but Bonnet tells 
us, that if boiled, all the parts of the pupa appear 3 , which 
proves the preexistence of these parts even when not to 
be discerned, and that nothing but the evaporation of 
the fluids in which they swim is wanted to render them 
visible. 

Mr. William MacLeay has with great truth observed: 
" The true criterion of animal as well as vegetable per- 
fection is the ability to continue the species b ;" and in 
their progress to this state certain changes take place in 
the parts and organs of all animals and vegetables : 
there is, therefore, an analogy in this respect between 
them ; and this analogy also furnishes another argument 
against Dr. Herold's hypothesis, as we shall presently 
see. These changes are of three kinds : In the vege- 
table kingdom, at least in the phaenogamous classes, there 
is a succession of developments terminating in the ap- 
pearance of the generative organs, inclosed in the flower ; 
in this kind the integuments, or most of them, are usually 
'persistent. In insects and other annulose and some ver- 
tebrate animals, there is a succession of spoliations, or 

-' QSuvr. viii. 315. b Hor. EiUum'olog. 446. 



58 STATES OF INSECTS. 

simultaneous changes of the whole integument, till the 
animal appears in its perfect form with powers of repro- 
duction ; in this kind the integuments are caducous. — In 
man and most of the vertebrate animals there is a gradual 
action of the vital forces in different organs till they are 
fitted for reproduction ; accompanied, as progess is made 
to the adult state, by the acquisition of certain organs, 
&c. as of teeth, horns, pubes, feathers, &c. a Let us now 
consider a little in detail the analogies that appear to exist 
between the second and the first and third kinds. I shall 
first consider the latter as the least obvious. That able, 
judicious, and learned physiologist, Dr. Virey, has pointed 
out no inconsiderable resemblance between the metamor- 
phosis of the insect, and the changes, which he denomi- 
nates a metamorphosis by metastasis, to which most ver- 
tebrate animals are subject. In them, he observes, a state 
analogous to the larva state begins at the exclusion of 
the foetus from the womb ; it is deprived of teeth, and its 
viscera are only accommodated to milk : in the cornute 
species the horns are in embryo : the digestive system 
now preponderates, and the great enjoyment is eating. 
A second state, in a degree analogous to that of pupa, 
commences at the period of dentition — the teeth now 
produce another modification in the intestinal canal, 
which becomes capable of receiving and digesting solid 
food : during this period the vital forces are all tending 
to produce the perfect state of the animal ; and in this 
state, in man especially, the individual is educated and 
fitted to discharge the duties of active life. Again, ana- 
logous to the imago state is the age of puberty, in which 

* See on this subject N. Diet. a" Hist. Nat. xx. article Metamor- 
phosis. 



STATES OF INSECTS. 59 

the complete development of the sexual powers takes 
place in both sexes, and the animal has arrived at its 
acme, and can continue its kind a : now the digestive 
powers diminish in their activity, and love reigns para- 
mount. When this state is fully attained, no further or 
higher change is to be expected, and the progress is soon 
towards decay and the termination of the animal's mortal 
career. So we see that in fact man and other mammalia, 
though they do not simultaneously cast their skins like 
the insect; or pass into a state of intermediate repose, 
before they attain the perfection of their nature, like the 
caterpillar ; have their three states, in each of which they 
acquire new parts, powers, and appetites. 

But a more striking analogy has been traced between 
the insects that undergo a complete metamorphosis and 
the vegetable kingdom ; for though the primary analogy 
seems to be between the Polypus and the Plant, yet the 
secondary one with the Insect is not by any means remote. 
There are circumstances to which I shall have occasion 
hereafter to call your attention, which afford some ground 
for supposing, that the substance of the insect and the 
vegetable partakes of the same nature, at least approxi- 
mates more nearly, than that of the insect and the verte- 
brate animal ; and every one who has observed these little 
creatures with any attention, will have observed amongst 
them forms and organs borrowed as it were from the 
kingdom of Flora; and vice versa the Botanist, if he 
makes the comparison, will find amongst his favourite 
tribes many striking resemblances of certain insects. 
But the analogy does not stop here ; for the butterfly 
and the plant appear to have been created with a parti- 

a N. Diet. d'Hisl. Nat. xx. 349—. 



60 STATES OF INSECTS. 

cular reference to each other, both in the epoch of their 
appearance and the changes that take place in them. 
Thus, as Dr. Virey has observed, the caterpillar is si- 
multaneous with the leaf of the tree or plant on which it 
feeds, and the butterfly with the flowers of which it im- 
bibes the nectar a . Swammerdam, I believe, was the first 
who noticed the analogy between the changes of the insect 
and the vegetable, and has given a table in which he has 
contrasted their developments, including other animals 
that undergo a metamorphosis b : an idea which has been 
generalized by Bonnet , and adopted and enlarged by 
Dr. Virey c . A state analogous to that of the larva in 
the insect begins in the plant when it is disclosed from 
the seed, or springs from its hybernaculum in the bulb, 
Sec, or is evolved from the gemma ; integument after in- 
tegument, often in various forms, as cotyledon, radical, 
cauline, or floral leaves, expands as the stem rises, all 
which envelopes incase the true representative of the 
plant, the fructification, as the various skins do the future 
butterfly. When these integuments are all expanded, 
the fructification appears inclosed by the calyx or corolla 
as the case may be, in which the generative organs are 
matured for their office — this is the bud, which is clearly 
analogous to the pupa state of the insect. Next the calyx 
and corolla expand, the impregnation of the germen takes 
place, and the seed being ripened, and dispersed by the 
opening of the seed-vessel or ovary of the plant, the in- 
dividual dies : thus the imago state of the insect has its 
representative in the plant. " If we place," says Dr. Virey, 
« here the egg of the insect, next its caterpillar, a little. 

3 iV. Did. d'Hist. Nat. xx. 348. 

b Bibl. Nat.m. Hill, ii. 138. c cEuvr. v. 283-. 



STATES OF INSECTS, €l 

further the chrysalis, and lastly the butterfly— what is 
this but an animal stem — an elongation perfectly similar 
to that of the plant issuing from the seed to attain its 
blossoming and propagation ? a 

There being, therefore, this general analogy in their 
progress to that state in which they can continue their 
species between every part of animated nature, it holds 
good, I think, that the same analogy should take place 
in their developments. If the adult man or quadruped, 
&c. is evidently an evolution of the foetus, as from mi- 
croscopical observations it appears that they are b , if the 
teeth, horns, and other parts, &c. to be acquired in his 
progress to that state are already in him in their embryos, 
we may also conclude that the butterfly and its organs, 
&c. are all in the newly-hatched caterpillar. Again, if the 
blossom and its envelopes are contained in the gemma, the 
bulb, &c. where they have been discovered c , it follows 
analogically that the butterfly and its integuments all 
preexist in its forerunner* 

Perhaps after this view of the objections to Dr. He- 
rold's hypothesis, it will not be necessary to say much 
with regard to the argument he draws from the change 
of organs— the loss of some and the acquisition of others 
— since this may readily be conceived to be the natural 
consequence of the vital forces tending more and more 
to the formation of the butterfly, and the withdrawing 
of their action more and more from the caterpillar ; I 
shall not, therefore, enter further into the question, espe- 

a N. Diet, d'Hist. Nat. xx. 355. 

b Leeuwenhoek discovered in the incipient foetus of a sheep, not 
larger than the eighth part of a pea, all the principal parts of the 
future animal. Arc. Nat. I. ii. 165, 173. 

c Bonnet, CEuvr. v. 284. 



62 STATES OF INSECTS. 

cially since the change of organs will come more regu- 
larly under our notice upon a future occasion. 

Winged insects, many branchiopod Crustacea, and the 
Batracian reptiles, have been observed by Dr. Virey to 
bear some analogy to the mammalia, aves, &c. in another 
respect. In leaving their egg, they only quit their first 
integument, answering to the chorion or external envelope 
of the human foetus ; they therefore still continue a kind 
of foetus, so to speak, more or less enveloped under other 
tunics, and principally in their amnios, or the covering 
in which the foetus floats in the liquor amnii*. This the 
butterfly does in the pupa case ; and its birth from this, 
under this view, will be the true birth of the animal. In 
the human subject, the ova upon impregnation are said 
to pass from the ovary through the Fallopian tube into 
the uterus. In the insect world, upon impregnation, the 
eggs pass first from the ovaries into the oviduct, answer- 
ing to the Fallopian tube, which in them terminates in 
the ovipositor, or the instrument by which the parent 
animal conveys the eggs to their proper station : there 
is, therefore, nothing properly analogous to the uterus in 
the insect, and the substance upon which the larva feeds 
upon exclusion answers the purpose of a placenta. 

After this general view of the most modern theories 
with regard to the metamorphosis of insects, I shall in the 
present and some following letters, treat separately of the 
different states through which these little beings suc- 
cessively pass. 

The first of these is the Egg state, the whole class of 
insects being strictly oviparous. Some few tribes indeed 

a A r . Diet, d'Hist. Nat. xx. 352, 



STATES OP INSECTS. 63 

bring into the world living young ones, and have on that 
account been considered as viviparous, but incorrectly, 
for the embryos of none of these are nourished, as in the 
true viviparous animals, within a uterus by means of a 
placenta, but receive their development within true eggs 
which are hatched in the body of the mother. This is 
proved by the observations of Leeuwenhoek, who found 
eggs in the abdomen of a female scorpion a ; and of 
Reaumur, with regard to the flesh-fly [Musca carnaria) 
and other viviparous flies as they have been called 5 . A 
similar mode of production takes place in vipers and 
some other reptiles, which have hence been denominated 
ovo-viviparous, to distinguish them from the true vivi- 
parous animals — the class Mammalia. By far the larger 
portion of insects is oviparous in the ordinary acceptation 
of the term. The ovo-viviparous tribes at present known 
are scorpions ; the flesh-fly and several other flies ; a 
minute gnat belonging to Latreille's family of Tipularice c ; 
some species of Coccus ,• some bugs (Cimicida) d ; and most 
Aphides, which last also exhibit the singular fact of indi- 
viduals of the same species being some oviparous and 
others ovo-viviparous, the former being longer in propor- 
tion than the latter. — Bonnet, however, is of opinion that 
the eggs of the first are not perfect eggs, but a kind of 
cocoon, which defends the larva, already formed in some 
degree, from the cold of winter e . 

a Select Works by Hoole, i. 132. The fact is confirmed by M. L. 
Dufour, who, having opened the abdomen of a female scorpion, found 
in the midst of some eggs nearly mature a little scorpion a quarter 
of an inch long ; it lay without motion, with its tail folded under the 
body. N. Bid. d'Hist. Nat. xxx. 426. 

b Reaum. iv. 425—. c Ibid. 428—. t. xxix./. 10, 11. 

11 Busch, a German author, affirms that many Cimicidce are subject 
to this law. Sckneid. i. 206. 

e Quoted in Huber Fourmis, 20S. Some reptiles also are at one 



64^ STATES OF INSECTS. 

When excluded from the body of the mother, or from 
the eag, as has been before observed, some insects appear 
nearly in the form of their parents, which, with a very 
slight alteration, they always retain; others, and the 
greater number, assume an appearance totally different 
from that of their parents, which they acquire only after 
passing through various changes. It is to these last, which 
have chiefly engaged the attention of Entomologists, 
that the title of metamorphoses has been often restricted. 
As, however, those insects which undergo the slightest 
change of form, as spiders do, undergo some change, and 
almost all insects cast their skins several times a before 
they attain maturity, Linne and most Entomologists, till 
very recently, have regarded the whole class as under- 
going metamorphoses, and as passing through four dif- 
ferent states, viz. the Egg — the Larva — the Pupa — and 
the Imago. 

It is obvious, however, that in ovo-viviparous species 
three states of their existence only come under our cog- 
nizance, as these, being hatched in the body of the 
mother, come forth first under the form of larvae. There 
is even one tribe of insects which presents the strange 
anomaly of being born in the pupa state. This is the 
Linnean genus Hippobosca (Pupipara fain. Latr.), to 
which our forest-fly belongs, the females of which lay 
bodies so much resembling eggs, that they were long 
considered as such until their true nature was ascertained 
by Reaumur (most of whose observations were confirmed 
by De Geer), who, from their size, which nearly equals 

time oviparous, and at another ovo-viviparous. N. Diet. d'Hist. 
Nat. xii. 568. 

a I say almost all insects, because the larvae of Hymenoptera and 
Dipt cm are supposed not to undergo this change. N. Diet. a" Hist. 
Nat. xx. 365. 



STATES OF INSECTS. 65 

that of the parent fly — from their slight motion when 
first extruded — from spiraculiform points which run down 
each side of them — and lastly, from their producing not 
a larva, as all other insects' eggs do, but perfect flies in 
the winged state — inferred, and doubtless with reason, 
that they are not real eggs, but pupae, or larva? just ready 
to assume the pupa state, which, however strange it may 
seem, have passed the egg and larva states in the body 
of the mother 3 . 

Insects, therefore, as to their mode of birth, may be 
divided into — 

I. Ovo-viviparous, subdivided into — 

1 . Larviparous, coming forth from the matrix of the 

mother in the state of larvae, as the Scorpion 
(Scorpio), the Flesh-fly (Musca), the Plant-louse 
(Aphis), &c. 

2. Pupiparous, continuing in the matrix of the mo- 

ther during the larva state, and coming forth in 
that of pupa, as the Forest-fly (Hippobosca 
equina), the Sheep-louse (Melophagus ovinus), 
the Bat-louse (Nycteribia Vespertilionis), &c. 

II. Oviparous. All other insects. 

Our business for the remainder of this letter will be 
with the latter description of these little animals. 
- The unerring foresight with which the female deposits 
her eggs in the precise place where the larvae, when ex- 
cluded, are sure to find suitable food ; and the singular 
instruments with which, for this purpose, the extremity 
of their abdomen is furnished, have been noticed in a 
former letter b , and those last mentioned will be adverted 
to in a future one. I shall now, therefore, confine myself 

a Reaum. vi. Mem. xiv. De Geer, vi. 280. 
b See Vol. I. Lett. xi. 
VOL. III. F 



66 STATES OF INSECTS. 

to other circumstances connected with the subject, ar- 
ranged for the sake of order under several distinct heads, 
as — their exclusion — situation — substance — number — size 
—figure — colour — and period of hatching. 

i. Exclusion. The exclusion or extrusion of the im- 
pregnated eggs takes place, when, passing from the ovary 
into the oviduct, they are conducted by means of the 
ovipositor, in which it terminates, to their proper situa- 
tion. By far the greater number of insects extrude them 
singly, a longer interval elapsing between the passage of 
each egg in some than in others. In those tribes which 
place their eggs in groups, such as most butterflies and 
moths, and many beetles, they pass from the ovaries 
usually with great rapidity ; while in the Ichneumonida?, 
Sphegidce, (Estri, and other parasitic genera, which usu- 
ally deposit their eggs singly, an interval of some minutes, 
hours, or perhaps even days, intervenes between the ex- 
trusion of each egg. One remarkable instance of the 
former mode I noticed in my letter on the Perfect Socie- 
ties of Insects 3 ; another may be cited, to which you may 
yourself be a witness — I allude to that common moth, 
vulgarly called the Ghost (Hepialus Humuli), which lays 
a large number of minute black eggs, resembling grains 
of gunpowder, and ejects them so fast that, according to 
De Geer, they may be said to run from the oviduct, and 
are sometimes expelled with the force of a popgun b . A 
Tetrapterous insect, the genus of which is uncertain, is 
said, when it is taken, to discharge its eggs like shot from 
a gun c . And a friend of mine, who had observed with at- 
tention the proceedings of a common crane-fly ( Tipida), 

a See Vol. II. p. 36. b De Geer i. 494—. 

e Called by M. l'Abbe Preaux, who observed it near Lisieux in 
Normandy, Mouche Batiste. N. Diet. cV Hist. Nat. xxi. 442. 



STATES OF INSECTS. 67 

assured me that several females which he caught pro- 
jected their eggs to the distance of more than ten inches. 

A few Diptera extrude them in a sort of chain or 
necklace, each egg being connected by a glutinous mat- 
ter with that which precedes and follows it. In a small 
species of a genus allied to Psychoda (a kind of midge), 
which one season was abundant in a window of my house, 
this necklace is composed of eggs joined by their sides, 
not unlike those strung by children of the seeds of the 
mallow 3 . Other Tipulidce on the contrary extrude their 
eggs joined end to end, so as to resemble a necklace of 
oval beads. Beris clavipes and Sciura Tho?nce, two other 
flies, produce a chain about an inch long, consisting of 
oval eggs connected, in an oblique position, side by side ; 
an arrangement very similar prevails in the ribband of 
eggs which drop from some of the Ephemerce h . 

These eggs, like those of the insects first mentioned, 
though connected, are expelled in succession ; but other 
tribes, as the Libellulidce, with the exception of Agrion, 
many Ephemerae, Trichopterous insects, &c. expel the 
whole at once, as it were in a mass. In those first men- 
tioned they are gummed together in- an oblong cluster . 
In one Ephemera mentioned by Reaumur d , they formed 
two oblong masses, each containing from three to four 
hundred eggs, and three and a half or four lines long. 
These animals as soon as their wings are developed eject 
these masses by two orifices, and are aided in the process 
by two vesicles full of air, wherever they happen to alight 
or to fall ; in most instances it is the water, their proper 
element, that receives them, but the animal does not ap- 
pear to know the difference between a solid and a liquid, 

a Plate XX. Fig. 20. b Reatim. vi. 509. t. XLj.f. U, 12. 

c Reaum. vi. 434. d Ibid. vi. 494. 

F 2 



68 STATES OF INSECTS. 

and seems only anxious how to free herself from a bur- 
then that oppresses her; all has been contrived that an 
insect so short-lived may finish her different operations 
with the utmost celerity : the term of her existence would 
not have admitted the leisurely extrusion of such a num- 
ber of eggs in succession 3 . Some Trichoptera, or May- 
flies, as Phryganea grandis L., exclude their eggs in a 
double packet, enveloped in a mass of jelly, (a circum- 
stance often attending the eggs that produce aquatic 
larvae,) upon the leaves of willows' 3 . A similar double 
packet in the year 1810 I observed appended to the anus 
of a blaek species with long antennas, probably Phry- 
ganea atrata F. c Upon taking several of the females I 
was surprised to find in the above situation a seemingly 
fleshy substance of a dirty yellow. At first, from its an- 
nular appearance, I conceived it to be some parasitic 
larva, but was not a little surprised upon pulling it away 
that it was full of globular transparent dusky eggs : it 
was about two lines and a quarter in length and nearly 
one in breadth. Being bent double it was attached to 
the animal by the intermediate angle, and when un- 
folded was constricted in the middle d . Each half, which 
was roundish, had about ten sharp transverse ridges, 
the interstices of which appeared as if crenated, an ap- 
pearance produced by the eggs which it contained. 
Upon more than gentle pressure it burst and let out 
the eggs. Though resembling the packet of P. grandis 
in shape and other circumstances, it was nothing like 

a The vesicles, which Reaumur thinks may be pulmonary vesicles, 
as well as assisting in the extrusion of the masses of eggs, he has 
figured t. xliv./. 10. uu. 

b De Geer ii. 534. t. xiii./. 13. 

c Coquebert Illustr. Ic. t. If. A. B. 

* Plate XX. Fig. 25, 



STATES OF INSECTS. 69 

jelly, but had rather a waxy appearance, and seems to 
have been covered by a membrane : so that the ex- 
cluded larvae must probably have eaten their way out 
of it. I have still by me, in 1822, specimens of these 
egg-packets, which, after the lapse of so many years, re- 
tain their original form and colour. It is not improbable 
that other species extrude their eggs in a similar case. 
Scopoli says of P. bicaudata L., that the female carries 
about under her belly her eggs united into a globe, like 
Lycosa saccata*. The eggs of Geometra Potamogata F. 
are also enveloped in a gelatinous substance, and the 
mass is covered with leaves' 5 . 

Insects of the Diptera order also, like frogs and toads, 
commit their eggs to the water imbedded in masses of 
jelly. Dr. Derham describes two different kinds of 
them, in one of which the eggs were laid in parallel rows 
end to end, and in another in a single row, in which the 
sides were parallel . But the most remarkable and 
beautiful specimen of this kind that I ever saw was one 
that, many years ago, I took out of a pond at Wittersham 
in Kent, from which I requested a young lady to make the 
drawing I send you d . The mass of jelly, about an inch 
and a quarter long, and rather widest in the middle, was 
attached by one end to some aquatic grass, and from one 
end to the other ran a spiral thread of very minute eggs, 
the turns of the screw being alternately on each side. 

The mode of exclusion of the eggs of the Blattte, which 
are engaged for a whole week in the business of oviposi- 
tion, is very singular : the female deposits one or two 
large suboviform capsules, as large as half their abdomen, 
rounded on one side, and on the other straight and ser- 

a Ent. Carniol. 269. n. 705. b Reaum. ii. 401. 

c In Raii Hist. Ins. 264. d Plate XX. Fig. 24. 



70 STATES OF INSECTS. 

rated, which at first is white and soft, but soon becomes 
brown and hard. This egg-case, as it may be called, 
contains sixteen or eighteen eggs arranged in a double 
series, and the cock-roaches when hatched make their 
escape through a cleft in its straight side, which shuts so 
accurately when they have quitted it, that at first it ap- 
pears as entire as before 3 . The insects of the genus 
Mantis also, or what are called the praying insects, when 
they deposit their eggs, eject with them a soft substance, 
which hardens in the air and forms a long kind of enve- 
lope resembling parchment, in which the eggs are ar- 
ranged also in a double series. And the Locusts {Gryl- 
lus Locusta L.) are said by Morier b to deposit in the 
ground an oblong substance, of the shape of their abdo- 
men, which contains a considerable number of eggs ar- 
ranged neatly in rows. The peristaltic motion observed 
in the females of some insects during oviposition has been 
before described c . 

ii. Situation. Under this head I include the situation 
in which the female insect places her eggs when extruded, 
whether she continues her care of them and carries them 
about till they hatch, or whether she entirely deserts 
them, placing them either without a covering within 
reach of their food, or enveloping them in hair or other- 
wise protecting them from accident or the attack of ene- 
mies. I shall consider them under two views : Jirst, as 
depositing their eggs in groups, whether covered or naked ; 
and secondly, as depositing them singly. 

• x Goeze Natarf. xvii. 183—. t. iv. /. 16—19. Corap. N. Diet. 
d'Hist. Nat. iii. 475. and xix. 239. De Geer iii. 533. 
b Second Journey through Persia, 100 — . 
c See Vol. II. p. 36. 



STATES OF INSECTS. 71 

1. Those that deposit their eggs in groups are first to 
be considered. I shall begin with those that protect them 
with some kind of covering. 

I have already mentioned in a former letter* the 
silken bag with which Lycosa saccala Latr., a kind of 
spider, surrounds her eggs, and in which she constantly 
carries them about with her, defending them to the last 
extremity. Many other spiders, indeed nearly the whole 
tribe, fabricate similar pouches, but of various sizes, 
forms, texture, and colours. Some are scarcely so big 
as a pea, others of the size of a large gooseberry ; some 
globular, some bell-shaped ; others, the genus Thomisus 
Walck. in particular, depressed like a lupine ; some of a 
close texture like silk ; others of a looser fabric resem- 
bling wool : some consisting of a single pellicle, but most 
of a double, of which the interior is finer and softer b ; 
some white ; others inclining to blue ; others again yel- 
low or reddish; most of them are of a whole colour, but 
that of Epeirajasciata is gray varied with black c . And 
while the parent spider of some kinds (the Lupi) always 
carries her egg-bag attached to her anus, others hold 
them by their palpi and maxillae ; and others suspend 
them by a long thread, or simply fasten them in different 
situations, either constantly remaining near them (the 
Telarice), or wholly deserting them (the Retiarice). The 
eggs of one of these last Lister describes as often fixed 
in a very singular situation — the cavity at the end of a 
ripe cherry ; and thus, as he expresses it — " Stomachi 
maxime delicatuli quoties hanc innocuam buccam non minus 
ignoranter quam avide devorarunt^P 

a Vol. I. p. 359—. 

b Latr. Hist. Nat. des Fourmis, 334. N. Diet. d'Hist. Nat. ii. 284. 
c Lister Be Aran. Tit. 13, 14. N. Diet. d'Hist. Nat. ii. 284. 
* Lister Ibid. 56. Tit. 15. 



72 STATES OF INSECTS. 

Herman informs us, that the species of the genus Che- 
lifer carry their eggs in a mass under their belly 3 . 

Madam Merian gives an account of two species of 
Blatta, which she affirms carry an egg-pouch about with 
them — one species (B. gigantea P) she describes as car- 
rying its eggs in a globular pouch of web like certain 
spiders, and the other in a brown bag, which, when 
alarmed, it drops and makes off b . But this admirable 
paintress of natural objects was not always correct in her 
statements c : it seems very improbable, from the habits 
of those species of which we know the history, that any 
of them should spin a pouch of web for their eggs. 

The only insects certainly known to spin an egg-pouch 
like the spiders, are the Hydrophili, a kind of water- 
beetles. Some of these, as H. lividus, carry them about 
with them, like Lycosa saccata, attached to the under 
side of their body, as M. Miger observed d ; and others 
when they are finished desert them. That of the great 
water-beetle {JHydrophilus piceus) was long ago described 
and figured by Lyonnet e ; and a more detailed account 
of it has since been given by M. Miger f . In form 
it somewhat resembles a turnip when reversed, since it 
consists of a pouch of the shape of an oblate spheroid, 
the great diameter of which is three quarters of an inch ; 
and the small, half an inch, from which rises a curved 
horn, about an inch long and terminating in a point g . 
The animal is furnished with a pair of anal spinners, 
which move from right to left, and up and down, with 

e N. Diet. d'Hist. Nat. xxvi. 447. b Ins. Surinam, t. i. 

c A striking instance of this may be seen in her forty-ninth plate, 
in which she has clapped the rostrated head of Fulgora laternaria 
upon the body of a Cicada Latr., affirming it to be the former fly in 
its previous state ! This might be a trick upon her. 

A N. Diet. d'Hist. Nat. xv. 489. c Lesser L. i. 300. 

1 Annates du Museum, xiv. 441. B Lesser L. i. t. W.f. xvi. 



STATES OF INSECTS. 73 

much quickness and agility : from these spinners a white 
and glutinous fluid appears to issue, that forms the pouch, 
which it takes the animal about three hours to construct. 
The exterior tissue is produced by a kind of liquid and 
glutinous paste, which by desiccation becomes a flexible 
covering impermeable to water ; the second, which en- 
velops the eggs, is a kind of light down of great white- 
ness, that keeps them from injuring each other. The 
tissue of the horn is of a silky nature, porous and shining, 
and greatly resembling the cocoons of Lepidoptera. This 
part, contrary to what Lyonnet supposes, appears calcu- 
lated to admit the air, the water soon penetrating it when 
submerged. At its base is the opening prepared for the 
egress of the larvae, when hatched, which is closed by 
some threads, that, by means of the air confined in the 
cocoon or pouch, hinder the water from getting in a . 
This nidus does not float at liberty in the water till after 
the eggs are hatched, the parent animal always attaching 
it to some plant. By means of this anomalous process 
for a beetle, which this insect is instructed by Providence 
thus to perfect, the precious contents of its little ark are 
secured from the action of the element which is to be the 
theatre of their first state of existence, from the voracity 
of fishes, or the more rapacious larvae of its own tribe, 
until the included eggs are hatched, and emerge from 
their curious cradle. 

I shall next amuse you with a few instances, in which 
the Allwise Creator instructs the parent insect, instead 
of defending her eggs with a covering furnished by her 
internal organs, to provide it from without, either from 

a Miger Ann. die Mus. ubi supr. Comp. N. Diet. d'Hist. Nat. xv. 
482-. 



74 STATES OF INSECTS. 

her own body or from some other substance. Most 
commonly, indeed, the female leaves her cluster of eggs 
without any other covering than the varnish with which 
in this case they are usually besmeared. Either they are 
deposited in summer and will soon be hatched, or they 
are of a substance calculated to encounter and resist the 
severities of the season. But many species, whose eggs 
are more tender or have, to resist the cold and wet of 
winter, defend them in the most ingenious manner with 
a clothing of different kinds of substance. 

Cassida viridis, a tortoise beetle, Rosel tells us, covers 
her group of eggs with a partially transparent membrane. 
Arctia Salicis F., a moth, common on willows, wholly 
conceals hers with a white frothy substance, which when 
dry is partly friable and partly cottony, and being insoluble 
in water effectually protects them from the weather 3 . The 
female of Lophyrus Pint (a saw-fly), having by means 
of her double saw made a suitable longitudinal incision 
in the leaf of a fir, and placed in it her eggs in a single 
row end to end, stops it up with a green frothy fluid 
mixed with the small pieces of leaf detached by her saws, 
which when dry becomes friable : a necessary precaution, 
since these eggs are extremely brittle b . Arctia cliry- 
sorhcea, Hypogymna dispar, and several other moths, sur- 
round theirs with an equally impervious and more singular 
clothing — hair stripped from their own bodies. With 
this material, which they pluck by means of their pincer- 
like ovipositor, they first form a soft couch on the sur- 
face of some leaf: they then place upon it successively 
layers of eggs, and surround them with a similar downy 
coating, and when the whole number is deposited cover 
a De G eer i. 192. b j bitL ii# 982> 



STATES OF INSECTS. 75 

the surface with a roof of hairs, which cannot be too 
much admired; for those used for the interior of the 
nest are placed without order, but those employed ex- 
ternally are arranged with as much art and skill as the 
tiles of a roof, and as effectually keep out the water, one 
layer resting partly on the other, and all having the same 
direction, so that the whole resembles a well-brushed 
piece of shaggy cloth or fur. When the mother has 
finished this labour, which often occupies her for twenty- 
four hours, and sometimes even twice that period, her 
body, which before was extremely hairy, is almost wholly 
naked — she has stripped herself to supply clothing to her 
offspring, and having performed this last duty she expires. 
The female moths which thus protect their eggs are often 
furnished with an extraordinary quantity of hair about the 
anus for this express purpose ; and Reaumur conjectures, 
that the singular anal patch of scales resembling those of 
the wings, but considerably larger, which is found in the 
female of Lasiocampa Pityocampa, is destined for the 
same purpose a . 

Reaumur had once brought to him a nidus of eggs 
clothed still more curiously : they surrounded a twig iri 
a spiral direction, like those of Lasiocampa Neustria, but 
were much more numerous, and were thickly covered with 
fine down, not pressed close, but standing off horizon- 
tally, which assumed much the same appearance as a 
fox's tail would if twisted spirally round a branch 5 . 

A procedure nearly similar was observed by De Geer 
in some species of Aphides (A. Alni and A. Pruni), which 
covered their eggs with a white cottony down detached 

3 Reaum. ii. 97. 159. b Ibid. 107—. t. iii./. 15. 



76 STATES OF INSECTS. 

from their belly by means of their hind legs a . In this 
case, however, the eggs were separately coated with the 
down, but there was no general covering to the group. 

Several insects make the leaves and other parts of 
plants serve as coverings for their eggs. Tenthredo 
Rosce L., a saw-fly, and other species of the same genus, 
with their saws make an incision in the green twigs of 
shrubs and trees, and fill it with a line of eggs placed end 
to end, taking care that, as the eggs grow after they are 
laid, they are placed at such distances as to leave room 
for their expansion 5 . Rhynchites Bacchus, a brilliant 
weevil, well known to the vine-dressers for the injury it 
does c , rolls with much art the leaves of the vine, so as to 
form a cavity, in which it places its eggs ; other species 
practise similar manoeuvres ; and some probably place 
their young progeny in the interior of twigs, making an 
opening for that purpose with their rostrum — at least, I 
once saw Rhynchites Alliarice L. with its rostrum plunged 
up to the antennae in the twig of a crab-tree. Others of 
this tribe, as we know, place their eggs in the interior of 
fruits and grain, as the nut, acorn, and common weevils. 

It is probable that most of the above coverings serve 
another purpose besides the protection of the eggs from 
wet and cold — that of sheltering them from the action of 
too great light, which, as Dr. Mich ell otti by numerous 
experiments has ascertained, is fatal to the included 
germe d . On this account it is perhaps that so many in- 
sects fasten their eggs to the under side of leaves. Those 



a De Geer iii. 48. 51. b Reaum. v. 122. 

c See above, Vol. I. p. 196. 202. 

d Journ. de Phys, Philos. Mag. ix. 244. 



STATES OF INSECTS. 77 

exposed in full day have usually an opaque and horny 
texture. 

Some insects are spared all trouble in providing a 
covering for their eggs, their own bodies furnishing one 
in every respect adapted to this purpose. Not to mention 
the Onisci, or wood-lice, since they rather belong to the 
Crustacea, which have a four-valved cell under the breast, 
in which they carry their eggs, as the kangaroo does its 
young in its abdominal pouch, the whole body of the fe- 
male of those strange animals the Cocci becomes a cover- 
ing for her eggs, which it incloses on every side. To make 
this intelligible to you, further explanation is necessary. 
You must have noticed those singular immovable tortoise- 
shaped insects, which are such pests to myrtles and other 
greenhouse plants. These are the young of a species of 
Coccus (C. Hesperidum L.), and their history is that of the 
whole race. Part of them never become much bigger than 
the size of which you ordinarily see them, and when full- 
grown disclose minute two-winged flies, which are the 
males. The size of the females, which glue themselves to 
a twig or leaf as if lifeless, now augments prodigiously, 
and the whole body, distended with the thousands of eggs 
which it includes to the bigness of a large pea, without 
any vestige of head or limb, resembles a vegetable ex- 
crescence or gall-apple rather than an insect. If you 
remove one of them, you will perceive that the under 
part of its abdomen is flat and closely applied to the 
surface of the branch on which it rests, only a thin 
layer of a sort of cotton being interposed between them. 
In laying her eggs the female Coccus does not, like most 
insects, protrude them beyond her body into day-light ; 
but as soon as the first egg has passed the orifice of her 



78 STATES OF INSECTS. 

oviduct, she pushes it between her belly and the cottony 
stratum just mentioned, and the succeeding eggs are de- 
posited in the same manner until the whole are excluded. 
You will ask how there can be found space between the 
insect's belly and the cotton, to which at first it was close- 
ly applied, for so large a mass of eggs ? To comprehend 
this, you must consider that nearly the whole contents of 
its abdomen were eggs ; that in proportion as these are 
extruded a void space is left, which allows the skin of 
the under side of the body to be pushed upwards, or 
towards that of the back, affording room between it and 
the cottony web for their convenient stowage. If you 
examine the insect after its eggs are all laid, yovi will find 
that they have merely changed their situation ; instead 
of being on the upper side of the skin forming the belly, 
and within the body, they now are placed between it 
(now become concave and nearly touching the back) and 
the layer of cotton. As soon as the female Coccus has 
finished her singular operation she dies ; but her body, 
retaining its shape, remains glued upon the eggs, to 
which it forms an arched covering, effectually protecting 
them, until they are hatched, from every external injury. 
Some species lay so many eggs, that the abdomen is not 
sufficiently large to cover the whole mass, but merely 
one side of it, the remainder being enveloped in cottony 
web a . 

I am next to consider the situation of those eggs that 

are excluded by the mother in groups without any other 

covering than the varnish with which they are usually 

besmeared in their passage from the oviduct. The fe- 

a Reaum. iv. Mem. i. 



STATES OF INSECTS. 79 

males only place them upon or near the food appropri- 
ated to the young larvae, to which they adhere by means 
of the varnish just mentioned. These groups consist of 
a greater or less number ; and when the eggs are hatched 
by the heat of the sun, the larvae begin to disperse and 
attack with voracity the food that surrounds them. It 
is thus that most butterflies and moths attach their eggs 
to the stems, twigs, and leaves of plants ; that the lady 
birds (Coccinella), the aphidivorous flies (SyrphiSac), and 
the lace-winged flies (Hemerobii), deposit them in the 
midst of plant-lice (Aphides); that the eggs of some flesh- 
flies are gummed upon flesh ; those of crickets and grass- 
hoppers buried in the earth ; those of gnats and other 
Tipulidans set afloat upon, or submerged in, the water. 

Frequently the whole number of eggs laid by one 
female is placed in one large group, more commonly, 
however, in several smaller ones, either at a distance 
from each other on the same plant, or on distinct plants. 
The object in the latter case seems to be, in some in- 
stances, to avoid crowding too many guests at one table, 
in others to protect the unhatched eggs from the voracity 
of the larvae first excluded, which would often devour 
them if in their immediate neighbourhood. 

In the disposition of the eggs which compose these 
groups much diversity prevails. Sometimes they are 
placed without order in a confused mass : more fre- 
quently, however, they are arranged in different, and 
often in very beautiful modes. The common cabbage- 
butterfly (Pieris Brassicce) and many other insects place 
theirs upon one end, side by side, so as, comparing 
small things with great, to resemble a close column of 
soldiers, in consequence of which those larvae which, on 



80 STATES OF INSECTS. 

hatching, proceed from the upper end, cannot disturb 
the adjoining eggs. Many indeed have a conformation 
purposely adapted to this position, as the hemisphaerical 
eggs of the puss-moth (Cerura Vinula), which have the 
base by which they are gummed membranous and trans- 
parent, while the rest is corneous and opaque. The 
same ready exit to the larva is provided for in the oblong 
eggs of the emperor moth (Saturnia Pavonia), which 
are piled on their sides in two or more lines like bottles 
of wine in a bin a . 

Where the larva does not emerge exactly from the 
end of the egg other arrangements take place. The 
whirlwig-beetle (Gyrinus natator) and the saw-fly of the 
gooseberry &c. (Tenthredo jiava L.) dispose theirs end 
to end in several rows ; the former upon the leaf of some 
aquatic grass, the rows being parallel 5 , the latter gummed 
to the main nerves of gooseberry or currant leaves, the 
direction of which they follow c . 

But the lackey-moths (Lasiocampa Neustria, castren- 
sis, &c.) adopt a different procedure. As their eggs, 
which are laid in the autumn, are not to be hatched until 
the spring, the female does not, like most other moths, 
place them upon a leaf, with which they might be blown 
by the winter's storms far from their destined food, but • 
upon the twig of some tree, round which she ranges them 
in numerous circles. If you examine your fruit-trees, 
you can scarcely fail to find upon the young twigs col- 
lections of these eggs, which are disposed with such ad- 
mirable art, that you would take them rather for pearls, 
set by the skilful hand of a jeweller, than for the eggs of 

a Rosel, ix. 157. t. 265? b Ibid. iii. 197. 

c See above. Vol. I. p. 195. 



STATES OF INSECTS. 81 

an insect. Each of these bracelets, as the French gar- 
deners aptly call them, is composed of from 200 to 300 
pyramidal eggs with flattened tops a , having their axes 
perpendicular to the circumference of the twig to which 
they are fastened, surrounding it in a series of from fif- 
teen to seventeen close spiral circles, and having their 
interstices filled up with a tenacious brown gum, which, 
while it secures them alike from the wintry blast and the 
attack of voracious insects, serves as a foil to the white 
enamel of the eggs that it encompasses. It is not easy 
to conceive how these moths contrive to accomplish so 
accurately with their tail and hind feet an arrangement 
which would require nicety from the hands of an artist ; 
nor could Reaumur, with all his efforts and by any con- 
trivance, satisfy himself upon this head. He bred num- 
bers of the fly from the egg, and supplied the females 
after impregnation with appropriate twigs ; but these, as 
though resolved that imprisonment should not force from 
them the secret of their art, laid their eggs at random, 
and made no attempt to place them symmetrically b . 

This illustrious Entomologist was more successful in 
discovering the mode in which another insect, the com- 
mon gnat, whose group of eggs is, in some respects, as 
extraordinary as that last described, performs its opera- 
tions. The eggs of this insect, of a long phial-like form, 
are glued together, side by side, to the number of from 
250 to 300, into an oblong mass, pointed and more 
elevated at each end, so as considerably to resemble a 
little boat in shape. You must not here suppose that I 
use the term boat by way of illustration merely ; for it 
has all the essential properties of a boat. In shape it 

a Plate XX. Fig. 14. b Reaum. i 95— /. 1—13. 

VOL. III. G 



8*2 STATES OF INSECTS. 

pretty accurately resembles a London wherry, being 
sharp and higher, to use a nautical phrase, fore and aft ; 
convex below and concave above ; floating, moreover, 
constantly on the keel or convex part. But this is not 
all. It is besides a life-boat, more buoyant than even 
Mr. Greathead's : the most violent agitation of the water 
cannot sink it ; and what is more extraordinary, and a 
property still a desideratum in our life-boats, though 
hollow it never becomes filled with water, even though 
exposed to the torrents that often accompany a thunder- 
storm. To put this to the test, I yesterday (July 25, 1811) 
placed half a dozen of these boats upon the surface of a 
tumbler half full of water ; I then poured upon them a 
stream of that element from the mouth of a quart bottle 
held a foot above them. Yet after this treatment, which 
was so rough as actually to project one out of the glass, 
I found them floating as before upon their bottoms, and 
not a drop of water within their cavity. 

This boat, which floats upon the surface of the water 
until the larvae are disclosed, is placed there by the female 
gnat. But how ? Her eggs, as in other insects, are 
extruded one by one. They are so small at the base in 
proportion to their length that it would be difficult to 
make them stand singly upright on a solid surface, much 
more on the water. How then does the gnat contrive 
to support the first egg perpendicularly until she has 
glued another to it— these two until she has fixed a 
third, and so on until a sufficient number is fastened to- 
gether to form a base capable of sustaining them in 
their perpendicular position ? This is her process. She 
fixes her four anterior legs upon a piece of leaf, or a 
blade of grass, and projects her tail over the water. She 



STATES OF INSECTS. 83 

then crosses her two hind legs, and in the inner angle 
which they form, retains and supports the first laid egg, 
as it proceeds from the anus. In like manner she also 
supports the second, third, &c, all of which adhere to 
each other by means of their glutinous coating, until she 
feels that a sufficient number are united to give a stable 
base to her little bark ; she then uncrosses her legs, and 
merely employs them to retain the mass until it is of the 
required size and shape, when she flies away, and leaves 
it to its fate floating upon the water*. 

It may not be out of place to mention here a re- 
markable circumstance which not seldom attends a kind 
of water-scorpion (Naucoris F.) occasionally to be met 
with in collections of Chinese insects. Its back is often 
covered with a group of rather large eggs, closely ar- 
ranged; but whether these are its own eggs or those of 
some large species of water-mite {Hydrachna Ma ill.) has 
not been clearly ascertained. On the former supposition, 
the ovipositor must be remarkably long and flexile to 
enable the animal to place the eggs on its back. In con- 
firmation of the latter it may be observed, that the spe- 
cies of the genus Hydrachna usually attach their eggs 
to the body and legs of aquatic insects, as for instance 
H. abstergens to the water-scorpion (Nepa cinerea), &c. b 

2. After having thus laid before you some of the pro- 
cedures of those insects that usually deposit their eggs 
in groups, either naked or defended by coverings of va- 
rious kinds, I next proceed to a rapid survey of those of 
the species that commonly deposit them singly. Some 

a Reaum. iv. 615—. t. xliv./. 2—7- 

,J N. Diet. d'Hist. Nat. xv. 445. Ros. iii. 156. 

G 2 



84 STATES OF INSECTS. 

of these, as for instance the Admiral Butterfly ( Vanessa 
Atalanta), glue each egg carefully to its destined leaf by 
alighting on it for a moment. Another butterfly (Hip- 
parchia Hyper -antlius) whose caterpillar is polyphagous, 
drops hers at random on different plants. In general it 
may be observed, that all those larvae which live in so- 
litude, as in the interior of wood, leaves, fruits, grain, 
animals, &c, proceed from eggs laid singly by the female, 
which is usually provided with an appropriate instrument 
for depositing them in their proper situation. Thus the 
nut- weevil {Balaninus Nucum Germ.) and also that of the 
acorn [B. Glandium) pierce a nut or an acorn with their 
long beak, and then deposit in the hole an egg, from 
which proceeds the maggot that destroys those fruits. 
Leeuwenhoeck asserts that the common weevil (Cala?i- 
dra granaria) adopts the same process, boring a hole in 
every single grain of corn before it commits an egg to it, 
and at the same time, by this manoeuvre, prepares a small 
quantity of flour to serve for the food of the tender grub 
when it is first hatched 3 . It is probable that the Rhyn- 
cophorous or weevil tribe in general chiefly use their beaks 
for the purpose of depositing their eggs in different vege- 
table substances, and perhaps principally in fruit or grain. 
The tribe of gall-flies (Cynips) on the contrary, whose 
economy, detailed in a former letter 5 , interested you so 
much, bore an opening for the egg with their spiral ovi- 
duct, which also conveys it. 

Another large tribe of insects depositing their eggs 

singly, are those which feed upon the bodies of other 

animals, into the flesh of which they are either inserted, 

or placed so as speedily to find their way into it. Some 

* Epist. 1687. b Vol. I. p. 448-. 



STATES OF INSECTS. 85 

of these introduce them into living animals, and then 
leave them to their fate, as the Ichneumons and gad-flies: 
others deposit them along with the dead body of an in- 
sect interred in a hole, often prepared with great labour, 
as the different species of sand-wasps (Sphecidce), spider- 
wasps (Pompilidcc), &c. : the manners of the latter of these 
tribes have been already adverted to a , and those of the 
Ichneumonidce will come more fully under consideration 
when I treat of the diseases of insects. 

A similar labour in providing suitable habitations for 
their eggs is undergone by vai'ious other insects whose 
larvae live chiefly on vegetable food, some inserting their 
egg within the substance the larva devours, as those that 
prey on timber, twigs, roots, or the like, and others on 
its surface. One would suppose at first, that the exceed- 
ingly small egg which produces the subcutaneous larvae 
would, by the parent moth, be imbedded in the substance 
of the leaf which is to exhibit hereafter their serpentine 
galleries : but this is not the case, for she merely glues it 
on the outside ; at least such was the situation of the only 
egg of these very minute moths Reaumur had ever an 
opportunity to observe b . 

Other insects, belonging to the tribe which lay their 
eggs singly, bury them in the ground. Of this descrip- 
tion are many of the lamellicorn insects, the dung-chafers 
(Scarabceidcs MacLeay) particularly, which, inclosing 
their eggs in a pellet of dung, deposit them in deep cy- 
lindrical cavities. Concerning the proceedings of some 
of these, as well as of the whole race of bees, wasps, &c, 
which all lay single eggs, I have before detailed to you 

a See above, Vol. I. p. 344—. b Reaum. iii. 8—. 



86 STATES OF INSECTS. 

many interesting particulars 3 . I must not conclude tins 
subject without observing, that the female Pycnogonida, 
an osculant tribe between Insects and Crustacea, carry 
their eggs upon two pair of false legs b . 

iii. Substance. From this long dissertation on the situ- 
ation of the eggs of insects and matters connected with it, 
I pass on to their substance or their external and internal 
composition, giving at the same time some account of the 
embryo included in them. The eggs of insects, like those 
of birds, consist in the first place of an external coat or 
shell, varying greatly, as to substance, in different genera. 
Most commonly, particularly in those which deposit their 
eggs in moist situations, as in dung, earth, and the like, 
it is a mere membrane, often thin and transparent, and 
showing, as in spiders, all the changes that take place in 
the inclosed embryo, as the formation of the head, trunk, 
and limbs c . This membrane is sometimes so delicate 
as to yield to the slightest pressure, and insufficient to 
protect the included fluids from too rapid an evaporation, 
if the eggs be exposed to the full action of the atmosphere. 
In most Lepidoptera, and several other tribes, this inte- 
gument is considerably stronger, in those moths whose 
eggs are exposed throughout the winter, as Lasiocampa 
Neustria, &c, so hard as not to yield easily to the knife. 
Even in these, however, its substance is more analogous 
to horn or a stiff membrane than to the shell of the eo-o-s 
of birds. Nothing calcareous enters into its composition, 
and it is not perceptibly acted upon by diluted sulphuric 

a Vol. I. 349-. 371—. " .V. Diet. d'Hist. Nat. xxviii. 271. 

e De Geer vii. 194, 



STATES OF INSECTS. 87 

acid. 1 he eggs of birds are lined by a fine membrane ; 
but I have examined several of those of insects, and 
have been able to discover nothing of the kind in them. 
I will not, however, affirm that it does not exist, though 
the shell of the insect egg appears more analogous to the 
membrane that lines that of the bird than to the outside 
shell itself. 

Within this integument is included a fluid, on the 
precise nature of which, except that it is an aqueous 
whitish fluid, few or no observations have been made, or 
indeed are practicable ; but it is reasonable to suppose 
that like the white and yolk of the bird's egg, it serves 
for the development of the organs of the germe of the 
future insect. 

But few observations are recorded that relate to the 
embryo included in the egg. It is stated, that it is in- 
vested with an extremely fine and delicate pellicle — sup- 
posed by some analogous to the Chorion and Amnios of 
the human foetus, though others think the shell of the 
egg to correspond with the Chorion, and the successive 
integuments of the larva with the Amnios*. When the 
egg is first laid, nothing indeed is to be seen in it but the 
fluid just mentioned ; the first change in this fluid is the 
appearance of the head of the embryo, more particularly 
in Coleoptera, of two points, the rudiments of the mandi- 
bles, and of those apertures into the tracheae which I 
have called spiracles b ; the little animal we may suppose 

* Compare N. Diet. d'Hist. Nat. xvi. 246. with xx. 352— j but as 
the Amnios immediately envelops the foetus, the pellicle seems most 
analogous to it, and the shell to the Chorion. 

b Swamm. Bibl. Nat. ed. Hill, h 133. a. Comp. N. Diet. d'Hist. 
Nat. xvi. 246. 



88 STATES OF INSECTS. 

then assumes its form and limbs. The embryo is usually 
so folded in the egg that the head and tail meet a , and 
the head, annuli, and other parts of the larva are often 
visible through the shell 5 . Swammerdam even saw the 
pulsation of the great dorsal vessel through the shell of 
the egg of Oryctes nasicornis. 

Under this head I must notice another singular cir- 
cumstance peculiar I believe to the eggs of insects, that 
sometimes, though rarely, they are covered with down or 
hair. Those of a singular little hemipterous insect, of a 
genus I believe at present undescribed, the ravages of 
which upon the larch have been before noticed c , are co- 
vered by a downy web, as is the case with the animal 
itself. De Geer has described the eggs of a bug, not 
uncommon in this country {JPentatoma juniperina Latr.), 
which are reticulated with black veins, in which very 
short bristles are planted d . I possess also a nest of 
brown eggs, probably of a species of the same genus, 
found upon furze, which appear to be covered with very 
short downy hairs. The top of these is flat, and sur- 
rounded by a coronet of short bristles, each surmounted 
by a small white ball, so as to wear the appearance of a 
beautiful little Macor. But hairy eggs are not confined 
to the Hemiptera Order, for, according to Sepp, those of 
the figure-of-eight moth (Bombyx ccerideocephala) are of 
this description 6 . 

iv. Number. The fertility of insects far exceeds that of 

a Swamm. Ibid. '> Sepp. iv. t. iii./. i. c. v. t. iv./. 2. 

c See above, Vol. I. p. 208: it is there called an Aphis, but it is a 
distinct genus. 

d De Geer iii. 245. t. xiii./. 20 — 22. 
e Sepp. iv. t. xiii./. 2. 3. 



STATES OF INSECTS. 89 

birds, and is surpassed only by that of fishes*. But the 
number of eggs laid by different species, sometimes even 
of the same natural family, is extremely various. Thus 
the pupiparous insects may be regarded as producing 
only a single egg ; Musca Meridiana L., a common fly, 
lays two b , other flies six or eight; the flea twelve; the 
burying beetle (Necrophorus Vespillo c ) thirty; May-flies 
{Trichoptera K.) under a hundred; the silk- worm moth 
about 500; the great goat-moth (Cossusligniperdd) 1,000; 
Acarus americanus more than 1 , 000 d ; the tiger-moth ( Cal- 
limorpha Caja) 1,600; some Cocci 2,000, others 4,000; 
the female wasp at least 30,000 e ; the queen bee varies 
considerably in the number of eggs that she produces in 
one season, in some cases it may amount to 40,000 or 
50,000 or more f ; a small hemipterous insect, resembling 
a little moth (Aleyrodes proletella Latr.) 200,000. But 
all these are left far behind by one of the white ants 
[Termes fatale F. bellicosus Smeath.) — the female of this 
insect, as was before observed s , extruding from her enor- 
mous matrix not less than 60 eggs in a minute, which 
gives 3,600 in an hour, 86,400 in a day, 2,419,200 in a 
lunar month, and the enormous number of 211,449,600 
in a year : probably she does not always continue laying 
at this rate; but if the sum be set as low as possible, it 
will exceed that produced by any other known animal in 
the creation. 

v. Size. The size of the eggs is in proportion to that of 

a The sturgeon is said to lay 1,500,000 eggs, and the cod-fish 
9,000,000. 

b Reaum. iv. 392. c See above, Vol. I. p. 350. 

d De Geer vii. 159. e See above, Vol. II. p. 109. 

i Ibid. 159. 166. s Ibid. 36—. 



90 STATES OF INSECTS. 

the insect producing them, though in some instances 
small ones produce larger eggs than those laid by bigger 
species. Thus the eggs of many Aptera, as those of that 
singular mite Urqpoda vegetans, and of the bird-louse 
found in the golden pheasant, are nearly as large, it is 
probable, as the parent insect ; while those of the ghost- 
moth (Hepialus Humuli) and many other Lepidoptera, 
&c. are vastly smaller. This circumstance perhaps de- 
pends principally on the number they produce : the ma- 
jority of them, however, are small. The largest egg 
known, if it be not rather an egg-case, is that of a spectre 
insect (Pkasma dilatatum), figured in the Linnean Trans- 
actions a , being five lines in length and three in width, 
which probably approaches near the size of that of some 
humming-birds. The largest egg of any British insect 
I ever saw was that of the common black rove-beetle 
(Staphylinas olens) sent me by Mr. Sheppard — this is a 
line and half long by a line in width. But we do not often 
meet with insect-eggs exceeding a line in length. A vast 
number are much smaller : those of Ephemeras are more 
minute than the smallest grains of sand b , and some almost 
imperceptible, as those of the subcutaneous moths, to the 
naked eye. Commonly the eggs laid by one female are 
all of the same size ; but in several tribes, those con- 
taining the germe of the female are larger than those that 
are to give birth to a male. This appears to be the case 
with those of the Rhinoceros beetle {Oryctes nasicornis c ), 
and according to Gould with those of ants d . As the 
female in a vast number of instances is much bigger than 
the male, it is not improbable that this law may hold 

* iv. t. xviii./. 4. 5. *> De Geer ii. 638. 

r Bibl. Nat, i. 132. b. ' Gould 36. 



STATES OF INSECTS. 91 

very extensively. It is stated, however, by Reaumur 3 , 
that the reverse of this takes place in the eggs of the 
hive-bee, those that are to produce males being larger 
than the rest. 

Another peculiarity connected with the present head is 
the augmentation in bulk which takes place, after exclusion, 
in the eggs of the great tribe of saw-flies ( Tenthredo L.), the 
gall-flies (Cynips L.), the ants [Formica L.) and the water- 
mites {Hy drachma Maill. Atax F.). Those of the two for- 
mer, which are usually deposited in theparenchymous sub- 
stance of the leaves, or of the young twigs, of various plants, 
imbibe nutriment in some unknown manner, through their 
membranous skins, from the vegetable juices which sur- 
round them b , and when they have attained their full size 
are nearly twice as large as when first laid. Except in the 
eggs of fishes, whose volume in like manner is said to 
augment previously to the extrusion of the young, there 
is nothing analogous to this singular fact in any other of 
the oviparous tribes of animals, the eggs of which have 
always attained their full size when they are laid. 

It is to M. P. Huber that we are indebted for the 
knowledge of the fact that the eggs of ants grow after 
being laid, a circumstance favoured probably by the 
moist situation in which the workers are always careful 
to keep them. By an accurate admeasurement he found 
that those nearly ready to be hatched were almost twice 
as big as those just laid c . A similar observation was 
made on the red eggs of a water-mite (Hydrachna abs- 
tergens) by Rosel, who conjectured that they draw their 
means of increase from the body of the water-scorpions 

:l Reaum. v. 477. b Ibid. iii. 579. v. 121. c Foarmis, 69—. 



92 STATES OF INSECTS. 

(Nepce), of which they form so singular an appendage 3 , 
which opinion is confirmed by De Geer, who observes 
that when the water-scorpions are covered by an unusual 
number of the eggs of the water-mites, they grow weak 
and languid, and endeavour to rid themselves of their 
parasitic appendages' 3 . It is most probable that the mite 
lately named ( Uropoda vegetans), which is often found 
planted as it were upon the bodies of various beetles, by 
means of a long pedicle, through which, as the foetus by 
an umbilical chord and placenta, it derives its nutriment 
from the above animals, is at first so fixed in the egg 
state, though before it is disengaged from the pedicle it 
is hatched, since it is often found with its legs displayed 
and quite active — this is the more probable, as the eggs 
of the water-mite are fixed by a pedicle to the animals to 
which they are attached c . I have met with a remarkable 
instance, in which pedunculated eggs seem to draw nu- 
triment from the mother, which brings the pedicle still 
near to the nature of the umbilical chord. Those of the 
small hemipterous insect which infests the larch before 
alluded to, are attached to the anal end of the mother by 
a short foot-stalk not longer than the ess. 

Dr. Derham seems to have observed, that the e&gs of 
some Diptera, of the tribe of Tipulidce, also increase in 
size before the larva is excluded d . It seems to me likely 
enough, that in this and many of the above cases in which 
the egg is supposed to grow, it is rather an extension of 
the flexile membrane that forms their exterior propor- 
tioned to the growth of the included embryo from food 

a Rosel iii. 152. b De Geer vii. 145. 

c Ibid. 123—. See above, Vol. I. p. 393. 
d Raii Hist. Ins. 265. 



STATES OF INSECTS. 93 

it finds within the egg, than from any absorption from 
without. 



vi. Shape. We are accustomed to see the eg-crs of dif- 
ferent species of oviparous animals so nearly resembling 
each other in form, that the very term egg-shaped has been 
appropriated to a particular figure. Amongst those of 
birds,"with which we are most familiar, the sole variations 
are shades of difference between a globular and oval or 
ovate figure. The eggs of insects, however, are confined 
by no such limited model. They differ often as much, 
both as to their shape, sculpture, and appendages, as one 
seed does from another; and it is not improbable that, 
if d i dy studied, they would furnish as good indications 
of generic distinctions as Gsertner has discovered in 
those of plants. Their most usual form indeed is glo- 
bular, oval, or oblong, with various intermediate modifi- 
cations. We meet with them ovate, or of the shape of 
the common hen's egg, flat and orbicular, elliptical, co- 
nical, cylindrical, hemispherical, lenticular, pyramidal, 
square, turban-shaped, pear-shaped, melon-shaped, boat- 
shaped, of the shape of an ale-stand, of a drum, &c. a , 
and sometimes of shapes so strange and peculiar, that 
we can scarcely credit their claim to the name of eggs. 
Thus the eggs of the gnat are oblong and narrow, or 
nearly cylindrical, having at the top a cylindrical knob b , 
so as to give them the precise form of the round -bottomed 
phial sometimes used by chemists : those of the common 

* Eggs of various shapes are given Plate XX. Fig. 3—23. See also 
Brunnich. Entomologia 4. N. Diet. d'Hist. Nat. xvi. 245. Reaum. if. 
t. iii. iv. xiv. xxvi. xxvii. &c. 

b Plate XX. Fig. 18. 



94? STATES OF INSECTS. 

water-scorpion (Nepa cinerea) are oblong, and at the 
upper end are surrounded by a sort of coronet, consisting 
of seven slender rays or bristles of the length of the egg % 
so as to resemble somewhat the seeds of Carduus bene- 
dictus (Cnicus acarna h ) of the old botanists. One would 
think this spinous circlet a very awkward appendage to 
bodies which are to be gradually extruded through the 
fine membranous ovaries and oviduct which inclose them : 
but they are so admirably packed, the unarmed end of 
each egg fitting closely into the space inclosed by the 
spines of the one next below it, or, rather, the spines 
which are moveable, embracing it closely, that not only 
is no room lost, but the ovaries are perfectly secure from 
injury. The eggs of another species of this tribe (Ra- 
natra linearis) have only two of these spines or bristles 
— they are inserted in the stem of a water-rush (Scirpus) 
or other aquatic plant, so as to be quite concealed, and 
are only to be detected by the two bristles which stand 
out from it e . The eggs of the beautiful lace- winged flies 
(Uemerobius), those golden-eyed insects so serviceable in 
destroying the plant-lice (Aphides d ), are still more sin- 
gular. Those of H. Perla are oval, and each of them 
attached to a filiform pedicle not thicker than a hair, 
and seven or eight times as long as the egg. By this pe- 
dicle (which is supposed to be formed by a glutinous 
matter attached to one end, which the female draws out 
by abstracting her ovipositor with the egg partly in it 

a Plate XX. Fig. 23. Swamm. Bill. Nat. t. iii. /. 7, 8. In a 
specimen I opened of this insect the bristles converged so as to form 
a kind of tail to the egg. 

b Darwin Phytolog. 512. 

Geoffr. Ins. Par. i. 480. t. x.f. ]. b. c. 

'' See above, Vol.. I. p. 2G1. 



STATES OF INSECTS. 95 

from the leaf, to which she has previously applied it, to 
a proper length, when the gluten becoming sufficiently 
solid she wholly quits the egg,) the eggs are planted in 
groups of ten or twelve on the surface of leaves and twigs, 
from which they project like so many small fungi, to some 
of which they have a remarkable resemblance. When the 
included larva has made Its way out of them by forcing 
open the top, they look like little vases, and were actually 
once figured by a Naturalist, as we learn from Reaumur, 
as singular parasitic flowers growing upon the leaves of 
the elder, for the origin of which he was extremely puz- 
zled to account 1 . Eggs similarly furnished with a pedicle 
are also laid by other insects ; but as most of these have 
been before alluded to, it is not necessary to describe them 
here 5 . The cause of these differences of form is for the 
most part concealed from us : in many instances it may 
perhaps be referred to that will to vary forms, and so to 
glorify his wisdom c and power, independently of other 
considerations, which, as Dr. Paley has well remarked d , 
seems often to have guided the Great Author of Nature. 
But in some cases the end to be answered is sufficiently 
evident. The long footstalks of the eggs of the Heme- 
robius just mentioned, there can be little doubt, are meant 
to place them out of the reach of the hosts of predaceous 
insects which roam around them, from whose jaws, thus 
elevated on their slender shaft, they are as safe as the 

a Reaum. iii. 386 — „ t. xxxii./. 1. t. xxxiii./. 5. 

b I allude to Ophion luteiim F. {Ichneumon L.) Vol. i. .Ed. 3. 
p. 269. figured Plate XX. Fig. 22; and the Hydrachnce or Trom- 
bidia. See above, and De Geer vii. 145. 

c From this circumstance called xoXvwow/of ootpia by the Apostle, 
Ephes. iii. 10. 

d Nat. Theol. 11th Ed. 375. 



96 STATES OF INSECTS. 

eggs of the tailor bird in its twig-suspended nest from 
the attack of snakes. Reaumur has described the eggs 
of a kind of fly, common upon the excrements of the 
horse and other animals (Scatophaga vulgaris Latr.), or 
one related to it, that requires to be immersed in the dung 
to which it is committed, on which the future grubs are 
to feed. He found that if not thus surrounded with 
moisture, they infallibly shrivelled up and came to no- 
thing ; but it is equally necessary that they should not be 
wholly covered : if they were, the young larva would be 
suffocated at its first exit from the egg. In what way is 
this nice point secured ? In this manner. Each egg is 
provided at its upper end, at which the animal when 
hatched comes out, with two diverging horns 3 ; these 
prevent it from being stuck into the excrement, in which 
the female deposits the eggs one by one, more than three- 
fourths of its length : and when examined they resemble 
not badly, as Reaumur remarks (except that their colour 
is white), a parcel of cloves stuck into a pudding, as they 
are neatly inserted at due distances in the disgusting 
mass b . The French Naturalists found these eggs in 
swine's dung ; I have observed them in cow-dung. La- 
treille thinks that the bristles above described attached 
to the eggs of Nepa and Ranatra have a similar use, as 
the female plunges them all but these bristles into the 
stems of aquatic plants c : but may not this have some- 
thing to do with their oxygenation? Reaumur has 
figured another egg of a dipterous insect which has a 
longitudinal wing or lateral margin attached to it, giving 

a Plate XX. Fig. 19. a a. 

b Reaum. iv. 376—. t. xxvii./. 9, 10. 

c Hist. Nat. gen. et partic. des Crust, et Ins. xii. 28.2. 



STATES OF INSECTS. 97 

it the form of an oblong square, the object of which, he 
conceives, is to give a greater surface by which it may 
be more firmly fixed to the substance against which the 
fly attaches it a . 

Besides these more striking variations in figure, their 
surface, though often smooth, is frequently curiously 
and most elegantly sculptured, a circumstance that di- 
stinguishes the eggs of no other oviparous animals. Some, 
as the margined egg just mentioned, are only sculptured 
on one side, the other being plain ; or, as those of the 
Tusseh silk- worm b (Attacus Papliia) and other Bombyces, 
which have orbicular depressed eggs with a central ca- 
vity above and below, have their circumference crossed 
with wrinkles corresponding with the rings of the inclosed 
embryo . Others again are sculptured all over. Of 
these, in some, the sculpture of the two sides is not sym- 
metrical, as in those of a fly figured by Reaumur d : but 
in general there is a correspondence in this respect be- 
tween the different parts of the egg. In those elegant 
ones before alluded to of some bird-louse attached to the 
golden pheasant, the shell resembles the purest wax, and 
is scored with longitudinal striae, each distinguished by 
a series of impressed points, which give it a beautiful ap- 
pearance of net-work. In the others, as in a common 
butterfly (Hipparchi a JEgeria) and moth (Geometra era- 
tcsgata), the whole surface is covered with hexagonal re- 
ticulations e . Others, as those of another butterfly (Hip- 

* Reaum. iv. 381. t. xxvi./. 19, 20. 

b Roxburgh in Linn. Trans, vii. 34. 

c Some of the Noctuas have similar eggs, as N. Lappa. Sepp iv. 
t. iii./. I.e. d Reaum. ubi supr.f. 22, 23. 

e Plate XX. Fig. 6. 8. 
VOL. III. H 



9$ STATES OF INSECTS. 

parchia Hyper an thus), are beset with minute granules or 
tubercles \ Others again, like those of the cabbage and 
hawthorn butterflies (Pieris Brassiccs and Cratagi), are 
remarkable for beautiful longitudinal ribs, often connected 
by elevated lines crossing them at right angles' 3 ; and in 
some, as in another butterfly (Hipparchia Furtina), crown- 
ed by imbricated scales . Many other minor differences 
in this respect might be noticed, but these will suflice to 
give some idea of the infinite variety exhibited in this 
respect by these little atoms. If the Creator has wrought 
them with so much art and skill, can it be beneath his 
reasonable creatures to examine and admire them, that 
they may glorify those attributes which they serve to il- 
lustrate ? 

Some eggs after exclusion occasionally become slightly 
corrugated: Malpighi supposed that this occurs only 
when the eggs are barren, having observed that those of 
the moth of the silk-worm which preserved their plump- 
ness always produced caterpillars, while those which lost 
their original rotundity and became wrinkled were con- 
stantly unprolific. Bonnet, however, found exactly the 
reverse take place in another moth d , so that these ap- 
pearances are scarcely to be depended upon. Kuhn as- 
serts, that a virgin female of the puss-moth {Cerura 
Vinula) having begun to lay eggs, which were yellow 
above, green below, and depressed, he introduced to her 
an hour afterwards a male, and some minutes subse- 
quently to the union, she again deposited eggs, which 
were m holly of a dark brown and convex e . 

a Plate XX. Fig. 5. » Ibid. Fig. 3. 4. 7. 9. he. 

c Ibid. Fig. 15. d Bonnet CEuvr. ii. 9. e Naturf. xiii, 229. 



STATES OF INSECTS. 99 

vii. Colour. The colour of the eggs of insects is as va- 
rious as their shape and sculpture. They are very often 
white, those of some spiders like minute pearls a ; some 
are yellow, as those of the silk-worm ; others orange, 
such are the eggs of the bloody-nosed beetle ( Timarcha 
tenebricosa) ; others again of a golden hue ; sometimes 
they are of a sanguine red. I remember once being 
much surprised at seeing the water at one end of a ca- 
nal in my garden as red as blood : upon examining it 
further I found it discoloured by an infinite number of 
minute red eggs, belonging probably to some dipterous 
insect of the Tipulidan tribe. There are also eggs of 
every intermediate shade between red and black ; some 
again are blue and others green. They are not always 
of whole colours, for some are speckled like those of 
many birds, of which I can show you specimens, that 
are also shaped like birds' eggs; these I think were 
laid by a common moth (Odenesis potatoria) ; others are 
banded with different colours — thus the blue eggs of the 
lappet-moth (Gastropacha quercifolia) are encircled by 
three brown zones b ; others are brown with a white 
zone c . 

Many eggs assume a very different colour after being 
laid a few days. In general upon their first exclusion 
they are white. Those of the chameleon-fly (Stratyomis 
Chamceleon) which I once found in great numbers, ar- 
ranged like tiles on a roof one laid partly over another, 
on the under side of the leaves of the water-plantain, from 
white become green, and then change to olive green. 
Those of the hemipterous enemy of the larch, more than 

a N. Diet. d'Hist. Nat. xvi. 245. b Reaum. ii. 286. 

c Plat£; XX. Fig. 11. Sepp t. iv.f. 2. 

H 2 



100 STATES OF INSECTS. 

once mentioned in this letter, are first mouse-col oured, 
then they assume a reddish hue, and lastly a blackish 
one. Those of the gnat from white in a short time as- 
sume a shade of green, in a few hours they are entirely 
green, and at length become gray a . Those of the silk- 
worm, which at first are of a yellow or sulphur colour, 
acquire a violet shade. The eggs of that rare moth En- 
dromis versicolor, are at first sulphur-coloured, then 
green, next rose-coloured, and lastly blackish. The 
colour of almost all eggs changes when they are near 
hatching; but this change depends more frequently upon 
the colour of the included larva, which appears through 
the transparent shell of the egg, than upon any actual 
alteration in the egg itself. 

viii. Period of hatching. The general rule for the 
hatching of the eggs of insects is the absorption by the 
embryo of all the superabundant moisture included in 
them ; but the time varies according to the state of the 
atmosphere, to the action of which they are subjected. 
Like those of other animals, they require a certain degree 
of heat for the due evolution of the included larva. This 
heat in much the greater number of instances is derived 
from the temperature of the air, but often also from 
other sources. The eggs of the gad-fly tribe are hatched 
principally by the heat of the body of the animal to which 
they are committed ; and doubtless the vital heat of va- 
rious larvae, small as it may be, must contribute some- 
thing to the hatching of the eggs deposited in them by 
various Ichneumons. In the fermenting bark in which the 
instinct of the rhinoceros beetles (Oryctes nasicornis &c.) 
a Reaum. iv. 617- 



STATES OF INSECTS. 101 

impels them to place theirs, the dung which the Scara- 
baidce select for that purpose, and the decaying vegeta- 
bles chosen by many other insects, a degree of artificial 
heat must exist : and the eggs, or rather egg-like pupee, 
of the spider-fly of the swallow {Ornithomyia Hirundinis) 
are hatched by the heat of those birds which sit upon 
them along with their own eggs. 

Fabricius says, " Insects never sit upon their eggs a ;" 
but certainly, as I formerly related to you b , the female 
earwig does this, and one would be induced to suppose, 
from the circumstance of the you' g ones following their 
mother, as chickens do the hen, that Pentatoma grisea 
[Cimex Linn.), formerly mentioned, may do the same c . 

With these exceptions, the eggs of all insects are 
hatched by atmospheric heat alone, the variations in 
which determine the more speedy or more tardy disclo- 
sure of the included insect. The eggs of such species as 
have several broods in the year, as the nettle butterfly 
( Vanessa Urticce), when laid in summer are hatched in a 
few days ; but if not laid till the close of autumn, they 
remain dormant through the winter, and are only hatched 
at the return of spring. That this difference is to be at- 
tributed to the influence of heat has been often proved 
by experiment: the autumnal eggs if brought into a 
warm room may be hatched as soon as those laid in the 
height of summer. Silk-worms' eggs naturally are not 
hatched till they have been laid six weeks, but in coun- 
tries where they are reared, the women effect their ex- 
clusion in a much shorter period by carrying them in 
their bosoms : yet to retard their hatching with particu- 

a Philos. Ent. 76. b See above, Vol. I. 358—. 

c See above, Vol. I. Ibid. 



102 STATES OF INSECTS. 

lar views is in many circumstances impossible. When 
the heat of the atmosphere has reached a certain point, 
the hatching cannot be retarded by cellars ; and M. 
Faujas has remarked, that in June the silk-worm's eggs 
would hatch in an ice-house a . 

The period of exclusion does not, however, depend 
solely upon temperature : the hardness or softness of the 
shell, and possibly differences in the consistence of the 
included fluid, intended to serve this very purpose, cause 
some eggs to be hatched much sooner than others exposed 
to the same degree of heat. Thus the eggs of many flesh- 
flies are hatched in twenty-four hours b ; those of bees and 
some other insects in three days; those of a common 
lady-bird {Coccinella bijpunctatd) in five or six days; 
those of spiders in about three weeks; those of the mole- 
cricket in a month; while those of many Lepidoptera and 
Coleoptera require a longer period for exclusion. The 
hard eggs of Lasiocampa Neustria and castrensis, noticed 
above, remain full nine months before being hatched , 
as do those of another moth (Hypogymna dispar\ which, 
though laid in the beginning of the warm month of Au- 
gust, do not send forth the included caterpillar till the 
April following 11 . We know no more of the cause of 

a Young's France, ii. 34. This author asserts, that no art will 
hatch the eggs of the common silk-worms the first year, or that in 
which they are laid ; but that there is a sort brought from Persia 
which are hatched three times a year, and which will hatch in fifteen 
days in the proper heat. In 1J65, it is said, the common sort hatched 
in the first year. Ibid. 226 — . 

b In the N. Diet. d'Hist. Nat. xii. 564. the eggs of the flesh-fly 
are said to hatch in two hours. This is true I believe in very warm 
weather. 

c Brahm. 310. <* Rimrod Naturf. xvi. 131. 



STATES OF INSECTS. 103 

this difference than of that which takes place in the 
period of exclusion of the eggs of the different species of 
birds. 

Some eggs change considerably both their form and 
consistence previously to being hatched. M. P. Huber 
found that those of different species of ants when newly 
laid are cylindrical, opaque, and of a milky white ; but just 
before hatching their extremities are arched, and they 
become transparent with only a single opaque whitish 
point, cloud, or zone, in their interior a . An analogous 
change takes place in the eggs of many spiders, which 
just before hatching exhibit a change of form corre- 
sponding with that which the included spider receives 
when its parts begin to be developed, the thin and flexible 
skin of the egg moulding itself to the body it incloses b . 

In proportion as the germe included in the egg is ex- 
panded, it becomes visible through the shell when trans- 
parent: this is particularly the case with spiders, in 
which, as was before observed, every part is very di- 
stinctly seen. At length, when all the parts are consoli- 
dated so as to be capable of motion, which in spiders 
takes place in four or five days after they begin to be 
visible in the egg, the animal breaks the pellicle by the 
swelling of its body and the movement of its legs, and 
then quits it, and disengages all its parts one after the 
other c . In general, at least where the shell is harder 
than that of spiders, insects make their way out by 
gnawing an opening with their mandibles in the part 
nearest their head, which, when the shell is very strong 
(as in Lasiocampa Neustria, &c), it is often several 

a Fourmis. 69. b De Geer vii. 195. c Ibid. 196. 



lOi STATES OF INSECTS. 

hours in accomplishing a . In many instances, however, 
the larva is spared this trouble, one end of the egg being 
furnished with a little lid or trap-door, which it has but 
to force up, and it can then emerge at pleasure : such 
lids are to be found in the eggs of several butterflies and 
moths, as Satyms Mara, Saturnia pavonia major, &c. 
and the common louse b . In those exquisitely elegant 
eg-ffs, before described, of some kind of bird-louse (Nir- 
mus) found adhering to the base of the neck feathers of 
the golden pheasant , there is a lid or cap of this kind 
of a hemispherical form terminating in a tortuous style. 
Those of a species of bug (Pentatoma Latr.), found by 
our friend the Rev. R. Sheppard, besides a convex lid 
are furnished with a very curious machine, as it should 
seem, for throwing it off. This machine is dark-brown, 
of a corneous substance, and of the shape of a cross-bow d , 
the bow part being attached to the lid or pushing against 
it, and the handle, by means of a membrane, to the upper 
end of the side of the egg. 

When the included animal has made its way out of 
the egg, it enters upon a new state of existence, that of 
Larva, to which I shall direct your attention in the fol- 
lowing letter. 

a Reaum. ii. 167. 

b Brahm. 249. Rosel. iv. 130. Swamm. Ml. Nat. t. If. 2. 

c By Mr. White, jun. cordwainer at Ipswich. 

d Plate XX. Fig. 16. a. 



LETTER XXX. 



STATES OF INSECTS. 

LARVA STATE. 

1 HE Larva state is that in which insects exist imme- 
diately after their exclusion from the egg (or from the 
mother in ovo-viviparous species), in which they usually 
eat voraciously, change their skin several times, and have 
the power of locomotion, but do not propagate. 

Almost all larvae, at their birth, are for a time in a very 
feeble and languid state, the duration of which differs in 
different species. In most it continues for a very short 
time, a few minutes or perhaps hours, after which they 
revive and betake hemselves to their appropriate food. 
In others, as in the generality of spiders, this debility 
lasts for seven or eight days, and in some species even a 
month, during which the young ones remain inactive in 
the egg-pouch a , and it is not till they have cast their first 
skin that their active state of existence commences. 

All larvae may be divided into two great divisions : — 

I, Those which in general form more or less re- 

semble the perfect insect. 

II. Those which are wholly unlike the perfect in- 

sect. 

a De Geer vii. 197. 



106 STATES OF INSECTS. 

I shall begin by calling your attention to the charac- 
ters of the fast of these divisions : the second, which is 
by far the most numerous, will be afterwards considered. 

I. The first division includes the larvae of Scorpions, 
Spiders, Cockroaches, Grasshoppers, Lanthorn-jlies, Bugs, 
&c. ; or generally, with the exception of the Flea and 
Crustacea, the whole of the Linnean Orders Aptera and 
Hemiptera. All these larvae, however remotely allied in 
other respects, agree in the general similarity which they 
bear to the perfect insects which proceed from them. 
The most acute entomologist, untaught by experience, 
could not even guess what would be the form of the 
perfect insects to be produced from larvae of the second 
division, while they can recognise the form of the spider, 
the cricket, the cockroach, the bug, and the frog-hopper, 
in that of the larvae. There are, however, differences in 
the degrees of this resemblance, according to which we 
may, perhaps, divide this tribe in their second state as 
follows : — 

i. Those that resemble the perfect insect, except in 
the relative proportions and number of some 
of their parts. 

ii. Those which resemble the perfect insect, except 
that they are apterous, or not yet furnished 
with organs of flight. 

i. Spiders, Phalangia, scorpions, lice, Podura, sugar- 
lice (Lepisma), mites, centipedes, millepedes, &c. come 
under thefirst subdivision. The larvae of the first six 
tribes here mentioned differ at their birth from the per- 
fect insect, only in size and the proportions of their parts. 



STATES OF INSECTS. 107 

Thus the larvae of spiders have their legs of a different 
relative length from that which they subsequently ac- 
quire ; and the palpi in the males, which previously to 
the discoveries of Treviranus were regarded as their 
sexual organs, are not yet fully developed a : and a si- 
milar difference takes place in the legs of Phalangia. 
The general form too of the body undergoes slight alter- 
ations, and the colour very considerable ones, with each 
change of the skin — a change to which all these tribes 
are subject. 

The larvae of the three last-mentioned tribes (the 
mites, centipedes, and millepedes) differ from the per- 
fect insect not only in the proportion but also in the 
number of their parts. Leeuwenhoeck states (and De 
Geer confirms his assertion, extending it to other species 
of mites b ), that the common cheese-mite, which in its 
perfect state has eight legs, when first excluded from the 
egg has but six, the third pair being wanting . Some 
however are born with eight legs, for instance A. eruditus 
of Schrank, which he saw come from the egg itself with 
that number d . Others again have never more than six 
legs : this is the case with Latreille's genera — Caris, 
Leptus, Atoma, and Ocypetes of Dr. Leach e . In the 
centipedes (Scolopendridce) and millepedes (Iulidce) dif- 
ferences still more remarkable, as I have stated in a for- 
mer letter, have been observed by De Geer ; these ani- 
mals, in their progress to the perfect state, not only gain 
several additional pairs of legs, but also several additional 
segments of the body. This illustrious Entomologist found 
that Polly xenus lagurus (Scolopendra~L.) was born a hexa- 

a De Geer vii. 197. b Ibid. 85. c Epist. lxvii. 1694. 390. 
d Enum. Ins. Ausir. bio. e N. Diet. <T Hist. Nat. i. 74. 



108 STATES OF INSECTS. 

pod, with but three segments and as many pairs of feet, 
but successively acquired five additional segments with 
other appendages, and nine more pairs of feet 3 . A spe- 
cies of millepede {lulus terresiris L.), which he also 
traced from its birth, and which begins the world at first 
with only eight segments and six feet, by a successive 
development at length acquires, in its perfect state, 50 
segments and not less than 200 feet b . The nature of 
these very singular accretions, which Latreille and Mr. 
Wm. MacLeay have also observed in the centipedes c , 
seems not well understood. If, as is most probable, 
though De Geer could not find any exuviae c , the larvae 
cast a skin before each change, they do not essentially 
differ from the metamorphosis of other insects. The 
legs that these insects thus acquire are affixed to the 
abdomen, the six that they set out with being attached 
to the part representing the trunk, so that the former 
may be regarded as analogous to the prolegs of cater- 
pillars. These animals therefore, as I have before inti- 
mated, invert the order of Nature, and from perfect de- 
generate into imperfect insects. 

ii. If you examine the cockroach, cricket, or grasshop- 
per, in different stages of their growth, you will find that 
the larva does not vary essentially from the perfect insect, 
except in wanting wings and elytra. The case is the 
same in almost all the Linnean genera of the modern 
crder — Hemiptera ; and with Raphidia, Termes, and 
Psocus, in the Neuroptera. Some of these, however, ex- 

, a De Geer vii. 576. b Ibid. 584. 

e Cojisiderat. Gener. 21. Horce Entomolog. 353. 
d De Geer, Ibid. Mr. W. MacLeay observes of the Chilopoda, or 
Centipedes, that they moult in the manner of Crustacea, ubi supr. 352. 



STATES OF INSECTS. 109 

hibit slighter discrepancies in the proportion of some of 
their parts, but without affecting the general resemblance. 
Thus the larvae of the common ear-wig have at first only 
eight, and subsequently nine joints to their antennae, 
whereas the perfect insect Yisls fourteen a ; and the forceps 
is quite different, resembling rather two straight styles 
than what its name implies. In those also of many bugs 
(Coreus marginatus F. &c), the joints of the antennas are 
of a shape dissimilar to that which obtains in the perfect 
insect. In that of the common water-scorpion, the anal 
air-tube, which is so long in the imago, is scarcely visi- 
ble b . In the Cicada tribe, so celebrated for their song c , 
neither the larva nor the imago have the enormous thigh 
armed below with strong teeth, the tibiae terminating in 
a fixed incurved claw, probably for the purpose of dig- 
ging the holes into which they retire till they disclose the 
fly, which distinguish the pupae of some species, and is 
particularly conspicuous in one commonly brought from 
China d . These often exhibit also other minor differences. 



II. In treating of the second great division of larvae, 
those that are wholly unlike the parent insect, — which 
includes, with few exceptions e , the whole of the Linnean 

a De Geer iii. 549. The figure of the forceps in De Geer (Ibid. 
L xxv. f. 21) is not quite correct. The styles do not taper to a point, 
but are filiform and acute. 

b Compare De Geer iii. t. xviii./. 2 and 13. q. 

c See above, Vol. II. p. 401. 

d Plate XVI. Fig. 4. c. Reaum. v. t.nix.f. 16. De Geer ubisupr. 
t. xxxii.y. 26. According to Reaumur, the larva as well as the pupa 
of Chermes Ficm has wing-cases (iii. 353). 

e These are in the female sex of some Coleoptera, as Lampyris, &c. 
which retain in the perfect state nearly the same form which they 
had when larvae. The larvae of some Staphylini are not very dissi- 
milar in form to the perfect insect. 



110 STATES OF INSECTS. 

orders, Coleoptera, Lepidoptera, Hymenoptera, Diptera, 
the majority of the Neuroptera, Coccus and Aleyrodes in 
Hemiptera, and the genus Pulex in Aptera, — I shall ad- 
vert to their characters, under several distinct heads; and 
to avoid unnecessary circumlocution, I shall in what fol- 
lows wholly leave out of consideration the Jirst division 
already explained, and use the term larva with reference 
only to those of the second. The heads under which I 
propose to treat of them are : The substance of their body, 
its parts, shape, or figure, clothing, colour. Also the 
Economy or mode of life of these creatures : their food, 
moultings, growth, age, sex, and their preparations for as- 
suming the Pupa?. 

i. Substance, with the exception of the head and six 
fore-feet, which are usually corneous, the exterior inte- 
gument or skin of larvae is commonly of a membranous 
texture, and the body is of a much softer consistence 
than in the perfect insect. In those, however, of some 
Staphylinida? and other Coleoptera, the dorsal part of 
the three first pieces, which represent the trunk of the 
perfect insect, is hard and horny. Some also have their 
whole skin coriaceous, as the tortoise-shell butterfly 
( Vanessa polychloros) ; and some few, as the wire-worm 
(Elater segetum), and other Elateres, very hard. I pos- 
sess a very remarkable larva from Brazil, from the ex- 
treme flatness of its body, and from its having cavities to 
receive its legs when unemployed, probably living under 
bark, the skin of which is still harder than that of the 
grub of the Elaters. Perhaps it has to resist great 
pressure ; and on that account is gifted with this quality, 
so seldom to be met with in other kinds of larva?. The 



STATES OF INSECTfj. Ill 

interior of the body of these animals is generally of a 
softer consistence than in the perfect insect. Their in- 
testines, and other internal organs, are usually wrapped 
in a voluminous substance of a fatty nature, which is re- 
garded as analogous to the epiploon, omentum, or caul, 
which envelops the viscera of quadrupeds, &c, and is 
called by Reaumur the corps graisseux. The use of this 
general flexibility of larvae is obvious ; for, their bodies 
being mostly long and narrow, a hard rigid covering 
would have been very inconvenient, and a considerable 
impediment to their motions. When a caterpillar is 
feeding, it has occasion to apply its body to any part of 
the margin of a leaf so as to support itself by its prolegs, 
and when moving it wants to give it all the curves that 
are necessary to enable it to avoid obstacles, and thread 
its way through the sinuous labyrinths which it must 
often traverse. On the other hand, the hardness of the 
substance of its head affords a strong fulcrum to the 
muscles which keep its powerful jaws in constant play. 
The larvae, indeed, of some Diptera have a membra- 
nous head; but their mandibles, which serve also as 
legs, are not grinders, but merely claws, the muscles of 
which require less powerful support 3 . Under this head 
it may be proper to observe, that generally larvae are 
opaque ; but some, as those of ants, and a few Lepido- 
ptera b , are diaphanous. That of Corethra crystallina 
(Tipula De Geer) is so beautifully transparent as to re- 

a The larvae described in the first Section, which resemble the 
imago, are usually covered with a skin not materially different from 
that of the insect in that state. 

b Huber Fourmis. 73; 2V". Diet. d'Jiist. Nat. vi. 250. 



112 STATES OF INSECTS. 

semble a piece of crystal, and scarcely to be distinguished 
from the water in which it lives a . 

ii. Parts. The body of each larva consists of the head, 
including its different organs, and of the succeeding seg- 
ments, of which the three first may usually be denomi- 
nated the trunk, and have the six anterior feet, when 
present, attached to their under side : the remainder is 
the abdomen. The latter includes in some species a vari- 
able number of membranous feet, as well as various ap- 
pendages affixed usually to its tail and sides. No larva 
is ever furnished with wings b . Each of these greater 
divisions, and the organs which they include, require 
separate consideration. 

1. Head. This, as was lately observed, is exteriorly of 
a horny substance, or at least harder than the rest of the 
body, in most larvae ; and on this account, though rarely 
separated from it by any visible distinct neck c , is, if the 

a Reaum. v. 40. t. xi.f. 4 — 15. 

b Midler, the Danish zoologist, relates, that he once met with a 
papilio which, with the true wings of the genus, had a head without 
antennae or tongue, furnished with mandibles; and, in short, that of a 
true caterpillar. It was a female, which deposited eggs that proved 
barren. If this solitary instance was not a mistake, is it possible that 
some parasitic larva had devoured only the inclosed head of the but- 
terfly, or so injured it that it could not reject the hard skin of the 
larva, and yet not be destroyed ? 

c The only larva? which have a visible distinct neck are those of 
some Dytisci, Staphylini, and a few others, in which this part is quite- 
distinct : proving the erroneousness of the opinion of those German 
entomologists, who consider the thorax as analogous to the neck of 
other animals, and hence call it Halsschttd. In some lepidopterous 
larva?, however, as in that of Pieris Brassicce, though no visible neck 
presents itself, one is very perceptible when the insect stretches the 
head forward considerably. Reaum. i, 460. 



STATES OF INSECTS. 113 

larva be of a tolerable size, distinguished at the first view. 
In those of many Dipterous insects, however, the head is 
covered with the same flexible membranous skin with the 
rest of the body, from which it is often scarcely to be di- 
stinguished. In these, except that it contains the organs 
of manducation, it wears no more the appearance of a 
head than any other segment of the body, and scarcely 
so much as the last or anal one. The head of these larvae 
is also remai'kable for another peculiarity, — that it is ca- 
pable of being extended or contracted, and assuming dif- 
ferent forms at the will of the insect : a property which 
the head of no superior animal can boast. It is probable 
that there is a considerable variety in the shape and cir- 
cumstances of the heads of larvae ; but since, with the ex- 
ception of those of Lepidoptera, they have had less at- 
tention paid to them than they deserve (indeed in a vast 
number of cases, from the difficulty of meeting with them, 
these variations, except in a few instances, have not been 
described), I will here mention a few of the most remark- 
able. The head of the young larva at its first exclusion 
from the egg is usually the most dilated part of the body, 
but it does not often continue so. In that of Cicindeld 
campestris, however, — the beautiful green beetle some- 
times found in sandy banks, — and also in several cater- 
pillars of Lepidoptera, it is much larger than any of the 
following segments 3 ; which, in conjunction with the 
animal's formidable jaws, gives it a most ferocious ap- 
pearance. In some lepidopterous larvae the head is of 
the same diameter with the rest of the body, but in in- 
sects in general it may, I think, be stated as less ; and 

» Plate XVII. Fig. 13. 
VOL, III. I 



lJ-t STATES OF INSECTS. 

occasionally it bears no proportion whatever to it. This 
is the case with the subcortical one from Brasil lately 
mentioned. It is more commonly longer than broad ; 
but in some, as in the larvae of carrion beetles (SilpJue), 
the reverse of this takes place. Its shape varies from 
triangular to orbicular, the mouth of the animal forming 
the vertex of the triangle. In some larvae of Hemerobii, 
however, the head is narrowest behind. That of the grub 
of a gnat noticed above [Corethra crystallina) forms a 
kind of sharp horn or claw, terminating the body ante- 
riorly a . The contour of the head of larvae is usually 
intire and unbroken ; but in the caterpillars of some Lepi- 
rlopfera, as the butterfly called thegrand admiral [Vanessa 
Atalanta), the Glanville fritillary (Melitcea Cinxia\ &c. 
it is divided into two lobes b . In the Brazil flat larvae it 
is trilobed, each lateral lobe being divided into three 
smaller ones : in which circumstance it somewhat resem- 
bles the head of some subcortical Cimicida. Although 

o 

the part we are treating of is generally without horns., 
yet in some tropical butterflies of the tribe of NympJiales, 
it is singularly armed with them. Thus Papilio Anchises 
is distinguished, according to Madame Merian c , by two 
in the occiput, which it has the power of retracting. In 
the purple highflier {Apatura Iris), a British species, the 

a Reaum. v. /. vi.f. 7. i.e. 

b In fact, in almost all Lepidopterous larvae the head may be re- 
garded as divided into two lobes or eye-shaped portions, which in- 
clude in the angle formed by their recession anteriorly from each 
other, the nasus (clypeus F.), the labrum, and other instruments of 
manducation. Posteriorly these lobes generally come into contact; 
but I have a specimen in which there is a narrow space between 
them. 

c Ins. Surinam, t. xvii. 



STATES OF INSECTS. 115 

two lobes of the head, I am informed, terminate behind in 
two horns ; as they do likewise in the brilliant Morpho 
Menelaus a , the lobes assuming the form of a pear, and 
the horn representing the stalk. In a caterpillar I found 
amongst Mr. Francillon's larvae, the head is bilobed, 
with a very long recurving subcapitate subramose spine. 
In Satyrus Cassia ; the head is armed with three occipital 
stout spines b . The larva of Nymphalis Amphinome Latr. 
(Limenitis F.) is crowned with a coronet of eight occipi- 
tal stout acute spines, the intermediate ones being the 
longest c ; and that of Morpho Teucer has a similar coro- 
net, consisting of only seven blunt rays, seemingly, rather 
than spines d . With regard to the articulation of the 
head with the trunk, it is generally by its 'whole diame- 
ter ; but in some instances, only by a part of it. This is 
the case with one of a sphinx figured by Mad. Merian e ; 
and I have another, probably belonging to the nocturnal 
Lepidoptera [Phalccna L.) f . In both these, the head is 
vertical and triangular ; and in the latter (which is a re- 
markable creature, the tail itself being more like a head, 
and furnished with what resemble two prominent black 
eyes) the vertex of the triangle is considerably higher than 
the back of the animal. Whatever may be the clothing of 
the body, the head is usually naked. Sometimes, however, 
it is itself beset with very small simple spines, as in the but- 
terfly of the mallow (Hesperia Malvce) ; or with longer 
compound ones, such as are found on the rest of the body. 

* Ins. Surinam, t. liii. b Ibid. t. xx-xii. c Ibid. t. viii. 

d Ibid. t. xxiii. e Ibid. t. xiv. 

f I purchased this singular caterpillar from the collection of the 
late Mr. Francillon, with his other exotic larvae; but without any 
indication of the fly to which it belonged. 

I 2 



11G STATES OF INSECTS. 

This is the case with one of a butterfly named by Rose!' 
Papilio morsa. The most common colour of the head of 
larva?, where it differs from the rest of the body, is a 
darker or lighter reddish brown, or piceous. This is 
particularly observable in those of Coleopterous insects y 
but it is very commonly in other tribes of the same hue. 
Sometimes, amongst the Lepidoptera, the head is of a 
different colour from the rest of the body; especially 
where a contrast renders it striking, I can show the ca- 
terpillar of some insect, probably of the hawk-moth tribe 
(Sphingida?), from Georgia, remarkable for the length of 
its anal spine, in which the body is black, and the head 
red : another has a white head and a brown body. In 
the larvae of some Lepidojitera, Coleoptera, and Diptera, 
the head can be wholly or nearly withdrawn within the 
first segment of the body. This may be readily seen in 
that of the common glow-worm; and that of a small gnat 
[Tipula rcplicata De Geer) withdraws it so completely 
that the anterior margin of that segment closes the ori- 
fice, so that the animal appears to have no head a . — 
The parts of the head which require distinct considera- 
tion are, the eyes, antennae, and the mouth .- consisting 
of various organs, which will be specified. Some of these 
parts and organs are peculiar to larva? of one order, 
others to those of another, and some are furnished with 
them all. 

Eyes. The larva? of many insects have no eyes. Those 
with antennae which terminate in a lamellated clava 
{ScarabcEus L.), and Capricorn beetles also {Cerambyx L.), 

a De Geer vi. 352. 



STATES OF INSECTS, 117 

amongst the Coleoptera, are without them, and probably 
several others ; and amongst the Diptera, all those with 
a membranous or variable head. Those of the remain- 
ing orders, with the exception, perhaps, of some Hymen- 
optera and Lepidoptera, are furnished with these organs; 
and in the Coleoptera all the predaceous tribes, as well 
as most of those that are herbivorous or granivorous, 
and the Gnats and other Tipulidans ( Tipularice Latr.) in 
the Diptera, are also distinguished by them. In the lar- 
vae of the dragon-flies (Libellula L.), and other Neuro- 
ptera, they are composed of many facets as in those of 
the perfect insect, from which they differ chiefly in being 
smaller. But in the other insects of this description they 
are simple, and resemble those of the Arachnida, and 
many aptera. These simple eyes vary in their number, 
in different genera and tribes, from one to six on each 
side of the head. Thus the larva of Telephorus, and the 
saw-flies, has only one a ; that of Cicindela three, the two 
posterior ones being large with a red pupil surrounded 
by a paler iris, which adds to the fierce aspect of this 
animal; and the anterior one very minute. Those 
of the tortoise-beetles also (Cassida) have three b ; of 
Staphylinus, four ; of Timarcha (the bloody-nosed beetle) 
Jive; of Carabus, and the Lepidoptera in general, six. 
In the last they are of different sizes, and generally ar- 
ranged in a circle: in that of Hemerobius, there are five in 
a circle, with one central one c . The appearance of these 

a De Geer iv. 68. ii. 922. 

b De Geer v. 170. 

c De Geer says, he could not make out the number of eyes of the 
larva of the whirlwig (Gyrinus) : probably, as in that of Dyliscus, 
there are six, iv. 382. 385. 



118 STATES OF INSECTS. 

globules, which are often not visible but under a power- 
ful lens, is so different from that of the eyes of a butter- 
fly or moth, or other perfect insect, that it has been 
doubted whether they actually perform the office of eyes, 
but without reason. They occupy the usual station of those 
organs, being situated in many instances upon a protube- 
rance which appears to incase them ; and seem of a con- 
struction closely analogous to that of the eyes of spiders, 
and the stemmata or ocelli of Hymenoptera, which have 
been satisfactorily proved to be organs of vision. In the 
larva of a moth not yet ascertained to exist in this coun- 
try, Attacus Tau, and probably other species, the eyes, 
after the skin has been changed a few times, are no longer 
to be seen a . 

Anlennte. Most larvae are provided with organs near 
the base of the mandibles, which from their situation and 
figure may be regarded as antenna?. Fabricius has as- 
serted that the larvae of the saw-flies ( Tenthredo L.) have 
no antennas; but in this he was mistaken, for though 
very short, they are discoverable in them, as he might 
have learned by consulting De Geer b . In the majority 
of Neuropterous larvae, they almost precisely resemble 
those of the perfect insect. In all the rest they are very 
different. The antennae of Coleopterous larvae are usu- 
ally either filiform or setaceous, consisting of four or five 
joints, nearly equal in length. Those of Lepidopterous 
larvae are commonly conical, as are those likewise of 
Chrysomela and Coccinella &c. amongst the Coleoptera, 
and very short, composed of two or three joints, of which 
the last is much thinner than the first, and ends in one or 

* Tez. 1 88. h iii 923, t. xxxvi./, i, b b. Fabr. P/dlos. Ent. (JO. 



STATES OF INSECTS. 119 

two hairs or bristles. These antennas the larva has the 
power of protruding or retracting at pleasure. Lyonnet 
informs us, that the caterpillar of the great goat-moth 
(Cossus ligniperda) can draw the joints of its antennas one 
within the other, so as nearly to conceal the whole 3 . 
The larva of the common gnat has two long incurved se- 
taceous antennas, fringed with hairs at some distance from 
their apex, which consist only of a single joint b . The 
greater number of Dipterous larvas, however, all indeed 
except the Tipulidans {Tipularice Latr.), and many be- 
longing to the Coleoptera and Hymenopiera orders (as 
those of Curcidio, Apion, Apis, &c), are wholly deprived 
of antennas. It is a general rule, that the antennas of 
larvas are shorter than the same organs in the perfect in- 
sect, the tribe ILphemerina perhaps affording the only 
example in which the reverse of this takes place c . 

Mouth. All larvas have a mouth situated in the head, 
by which they receive their food, and furnished with one 
or more instruments for the purpose of mastication and 
deglutition. These instruments, in all the orders except 
Lejridoptera, some Neuropte?-a and Diptera, bear a ge- 
neral resemblance to the same parts in the perfect insect. 
In larvas of the Coleopterous, Lepidopterous, and Hy- 
menopterous orders, we can distinguish for the most part 
an upper and under lip; two pairs of jaws answering to 
the mandibulas and maxillae ; and two, four, or six pal- 
pi 11 : and some of these instruments may be found in 
most Diptei-a. Each of these parts require separate no- 
tice. 

Upper-lip (-Lab-rum). The mouth of almost all larvas, 

a Lyonnet 41. t. ii./. I.e. b De Geer vi. 307- 

c Ibid. ii. /. xvi. Comp./. 2 a a with/. 14 a a. 

d In the larva of Cicindela there are six palpi, as in the perfect insect.. 



120 STATES OF INSECTS. 

except some of the order Diptera, are provided with a 
distinct upper-lip, for retaining their food during masti- 
cation. As the construction of this part does not widely 
differ from that of the perfect insect, which will hereafter 
be more fully described, it is only necessary to observe, 
that it is usually a transverse moveable plate, attached 
posteriorly to the nasus [clypeus F.), and situated just 
above the mandibles a . 

Upper-jaws (Mandibul.e). The most usual figure of 
these, which are of a hard horny consistence b , is that of 
two slightly concave, oblong, or triangular plates, often 
at their lower extremity of considerable thickness, and of 
very irregular form, the base of which is filled with 
powerful muscles, and planted in the side of the mouth 
so as to move transversely. The other extremity can be 
made to meet or diverge like the claws of pincers, and 
are divided into one or more tooth-like indentations, by 
means of winch the food of the larva is cut c . This is 
their construction in the larvae of all Lejndoptera, and in 
many of those of the other orders. They frequently, 
however, assume a different form, though their situation 
is always the same. Thus in the larvae of the Capricorn 
beetles {Ceranibyx L.) and of other wood-boring species, 
they are shaped like the half of a cone, the inner sides of 
which, applying close to each other, form a pair of power- 
ful grindstones, capable of comminuting the hardest tim- 

a Lyonnet, t. \.f. 7. e. In the larva of Callidium violaceum, how- 
ever, this part is of a singular shape, being orbicular. Kirby Linn. 
Trans, v. I. xii./. 12. a. 

b It is affirmed ("iV. Diet. cVHist. Nat. vii. 333) that the larvae of 
those Coleoplera that live in carcases have mandibles almost mem- 
branous : those, however, of that of Silpha rugosa are horny and 
hard. 

c Lyonnet, /. luf. 1. r> d, and/. 2, 3, 4. 



STATES OF INSECTS. 121 

ber a . M. Cavier has observed, with regard to the man- 
dibular of those of stag-beetles (Lucanus), that besides 
their teeth at the extremity, they have towards their base 
a flat striated molary surface ; so that they both cut and 
grind their ligneous food b . It seems to have escaped 
him, that a similar structure takes place in many perfect 
insects of the lamellicorn tribe, as I shall hereafter show 
you. In the larvae of the water-beetles (Dytiscus L.), 
ant-lions (Myrmeleon L.), and lace-winged flies (Hemero- 
bins L.), they resemble somewhat the forceps at the tail 
of an ear-wig, being long and incurved ; and, what is more 
remarkable, hollow and perforated at the end, so as to 
serve as a channel for conveying into the larva's mouth 
the juices of the prey which by their aid it has seized. 
Reaumur even asserts, that the larva of Myrmeleon has 
no other entrance into its throat than through these tu- 
bular mandibles c . That of the rove-beetles (Slap/iy- 
linus L.), and of many other Coleopterous genera, have 
these organs of this forcipate construction, without being 
perforated" 1 . In the larva of the carnivorous flies, and 
many other Diptera, are two black incurved subulate 
parts, connected at the base, and capable of being pro- 
truded out of, and retracted into, the head, through the 
skin of which they are usually visible. As I informed 
you in a former letter e , these mandibles are used for 
walking as well as feeding : they are parallel to each 
other, and are neither formed for cutting nor grinding 

a Kirby in Linn. Trans, v. t. xii./.7 b. 
b Cuvier Anat. Covip. hi. 322. c Reaum.Vi. 340. 

d The larva of Cicihdela campestris has mandibles of this descrip- 
tion. Plate XVII. Fir,. 13. c c. 
e See above, Vol. II. 275 — . 



122 STATES OF INSECTS. 

like the mandibles of other insects, but merely detach 
particles of food by digging into it and tearing the fibres 
asunder. In this operation they are probably assisted by 
an acutely triangular dart-like instrument of a horny sub- 
stance, which in some species (Musca vomitotia) is 
placed between the two. In others this part is wanting. 
Some Dipterous larvaa have two similar mandibles, but in- 
stead of being parallel, they are placed one above the other; 
©tliers (Mmca domestica and meridiana) have but one such 
mandible, and some have no perceptible mandible of any 
kind. The mandibles of the larva of the crane-flies ( Tipula\ 
which are transverse and unguiform, do not act against 
each other, but against two other fixed, internally coiir 
cave and externally convex, and dentated pieces a . 

Under-jaws (Maxilla). These are a pair of organs, 
usually of a softer consistence, placed immediately under 
the upper-jaws; but as they are usually so formed and si- 
tuated as not to have any action upon each other, it is 
probable that in general they rather assist in submitting 
the food to the action of the mandibular, than in the com- 
minution of it. In Lepidopterous larvae they appear to 
be conical or cylindrical (at least in that of the cossus 
so admirably figured by Lyonnet b ), and to consist of two 
joints; which may, I imagine, be analogous to the upper 
and lower portions of which the maxillae of perfect insects 
usually consist. The last of these joints is surmounted 
by two smaller jointed palpiform organs. If any part of 
the maxillae can act upon each other, it is these organs 
or palpi ; but it is evident they are not calculated for mas- 
tication, although they may assist in the retention of the 

- 1 Reaum. v. 9. i.lf. 4. c c. IL h Traite Anatom. i. W.f. 1. h h. 



STATES OF INSECTS. 123 

substance to be masticated. In a figure given by Reau- 
mur of the under side of the head of another lepidopte- 
rous larva (Ermine® Pomonella), the maxillae consist of 
a single joint, and appear to be crowned by chelate pal- 
pi a : a circumstance which is also observable in that of a 
common species of stag-beetle (Lucanas parallelipipedus\ 
the weevil of the water-hemlock (Lixus paraplecticus h \ 
and other insects. In general the maxilla? of larvae are 
without the lobe or lobes discoverable in those of most 
perfect insects, this part being usually represented by a 
kind of nipple, or palpiform jointed process, strictly ana- 
logous to the interior maxillary palpi of the predaceous 
coleoptera; but in most of the lamellicorn beetles the 
lobe exists in its proper form e , as it does likewise in that 
of the capricorn-beetle before noticed (Callidium viola- 
ceu?n d ). In the former instance, it is armed with spines or 
claws; but in the latter it is unarmed, and rounded at the 
end. In the larva of Cicindela campedris^ the base of the 
maxilla runs in a transverse direction from the mentum, 
to which, as is usually the case, it is attached. From this 
at right angles proceeds the lobe, from the outer side of 
which the feeler emerges; and the inner part terminates 
in an unguiform joint, ending in two or three bristles. 
The structure in the larvae of water-beetles (Dytiscus'L.) 
is different, for they appear to be without maxillae e ; but 
the case really seems to be, that these organs are repre- 
sented by the first joint of what M. Cuvier calls their 
palpi f ; from which proceed the real palpi, the interior 

a Reaum. ii. t. 40./. 4. l ' De Gccr v. 229. 

c Ibid. iv. t. xi.f. lb', pp. d Linn. Trans, v. t. xu.f. 10. 

e Cuvier Anat. Camp. iii. 323. 

' De Geer iv. /. xv.f. 9. b h. The exterior and interior palpi arc 
both represented in this figure. 



124 STATES OF INSECTS. 

one being very short, and consisting only of a single 
joint. These maxillae of larvae were regarded by Reau- 
mur and other writers as parts of the under-lip, on each 
side of which they are situated ; and indeed, as well as 
those in the perfect insect, they form a part of the same 
machine, being connected by their base with the mentum, 
which is part of the labium, but they are clearly analo- 
gous to the maxillae of the imago. They are not to be 
found in the larvae of many Dipterous insects, and per- 
haps in some species belonging to other orders. In some 
Neuropterous larvae, as those of the Libellulina MacLea}^, 
the maxillae are of a substance quite as solid and horny as 
the mandibles, which in every respect they resemble a . 

Under-lip (Labium). Between the two maxillae in the 
larvae of most of the insects under consideration is a part 
termed by Reaumur the middle division of the under-lip, 
but which is in fact analogous to the whole of that organ 
in the imago. This organ varies in shape, being some- 
times quadrangular, often conical, &c. Interiorly it is 
frequently connected with a more fleshy protuberance, 
called the tongue by Reaumur b , and supplying the place 
of the ligula in the perfect insect. On each side of the 
apex of the under-lip is a minute feeler, and in the mid- 
dle between these in the Lepidoptera and many others, is 
a filiform organ, which I shall call the spinneret (Fusidus), 
through which the larva draws the silken thread em- 
ployed in fabricating its cocoon, preparatory to assuming 
the pupa state, and for other purposes c . This organ is 

a Reaum. vi. t. xxxvii./. 5. e e. h Ibid. i. 125. 

c Plate XXI. Fig. 9. The organ with which the larvae of Heme- 
robius, Myrmeleon, and Hydrophilus, spin their cocoons, is situated 
in the anus. The spinneret of the Cossus is figured by Lyonnet Ana- 
iom. t. u.f. 1. l, and jig. 9. 



STATES OF INSECTS. 125 

found only in those larvae which have the power of spin- 
ning silk ; that is, in all Lepidopte?-a, most Hijmenoptera, 
Trichopiera, some Neuroptera, and even a Dipterous in- 
sect a . This tube, Lyonnet had reason to believe, is com- 
posed of longitudinal slips, alternately corneous and mem- 
branous, so as to give the insect the power of contracting 
its diameter, and thus making the thread thicker or 
smaller. There is only a single orifice at the end, which 
is cut obliquely, somewhat like a pen, only with less obli- 
quity, and without a point, the opening being below, so 
as to be conveniently applicable to the bodies on which 
the larva is placed. Reaumur conceived that this spin- 
neret had two orifices ; but Lyonnet ascertained this to 
be a mistake, the two silk tubes uniting into one before 
they reach the orifice. From the contractile nature of 
the sides and the form of the orifice, combined with the 
power the insect has of moving it in every direction, re- 
sults the great difference which we see in the breadth and 
form of the threads, some being seven or eight times as 
thick as others, some cylindrical, others flat, others chan- 
nelled, and others of different thickness in different parts b . 
In the larvse of many Diptera the under-lip is merely a 
small tubercle, which can be protruded from the insect's 
mouth by pressure c . 

One of the most remarkable prepensile instruments, in 
which the art and skill of a Divine Mechanician are 
singularly conspicuous, and which appears to be without 
a parallel in the insect world, may be seen in the under- 
lip of the various species of dragon-fly (Libellula L.). In 

a De Geer vi. 3/0. This species (Tipula Agarici seticornis De Geer) 
lias two separate spinnerets, t. xx./. 8. m m. 

b Lyonnet 55 — . e Reaum. iv. IGG. 



12G STATES OF INSECTS. 

other larvae this part is usually small and inconspicuous, 
and serves merely for retaining the food and assisting in 
its deglutition; but in these it is by far the largest organ 
of the mouth, which when closed it entirely conceals ; 
and it not only retains but actually seizes the animal's 
prey, by means of a very singular pair of jaws with which 
it is furnished. Conceive your under-lip (to have re- 
course, as Reaumur on another occasion a , to such com- 
parison,) to be horny instead of fleshy, and to be elon- 
gated perpendicularly downwards b , so as to wrap over 
your chin and extend to its bottom, — that this elongation 
is there expanded into a triangular convex plate c , at- 
tached to it by a joint d , so as to bend upwards again and 
fold over the face as high as the nose, concealing not 
only the chin and the first-mentioned elongation, but the 
mouth and part of the cheeks c : conceive, moreover, that 
to the end of this last-mentioned plate are fixed two other 
convex ones, so broad as to cover the whole nose and 
temples f , — that these can open at pleasure, transversely 
like a pair of jaws, so as to expose the nose and mouth, 
and that their inner edges where they meet are cut into 
numerous sharp teeth or spines, or armed with one or 
more long and sharp claws s : — you will then have as ac- 
curate an idea as my powers of description can give, of 
the strange conformation of the under-lip in the larvae of 
the tribes of Libellulina ; which conceals the mouth and 
face precisely as I have supposed a similar construction 
of your lip would do yours. You will probably admit 

a Reaum. v. 135. b Ibid. vi. t. xxxvii./. 7. b p. ' Ibid, m c e. 

d Ibid./. 6. p. e Ibid. Compare/. 4 with/. 6, 7. 

r Ibid. t. xxxvi./ 12. s a e. 

s Ibid, n e, and xxxviii./. 7, dc; De Geer ii. /. xix./. 17. d g. 



STATES OF INSECTS. 127 

that your own visage would present an appearance not very 
engaging while concealed by such a mask; but it would 
strike still more awe into the spectators, were they to see 
you first open the two upper jaw- like plates, which would 
project from each temple like the blinders of* a horse; 
and next, having by means of the joint at your chin let 
down the whole apparatus and uncovered your face, em- 
ploy them in seizing any food that presented itself, and 
conveying it to your mouth. Yet this procedure is that 
adopted by the larvse provided with this strange organ. 
While it is at rest, it applies close to and covers the face. 
When the insects would make use of it, they unfold it 
like an arm, catch the prey at which they aim by means 
of the mandibuliform plates, and then partly refold it so 
as to hold the prey to the mouth in a convenient position 
for the operation of the two pairs of jaws with which they 
are provided. Reaumur once found one of them thus 
holding and devouring alarge tadpole; — a sufficient proof 
that Swammerdam was greatly deceived in imagining 
earth to be the food of animals so tremendously armed 
and fitted for carnivorous purposes. Such an under-lip 
as I have described is found in the tribe of dragon-flies 
{JLibellulind) ; varied, however, considerably in its figure 
in the different genera. In the larva of Libellula Fab., 
such as Libelhda depressa, &c. it is of the shape above 
described ; so exactly resembling a mask, that if Ento- 
mologists ever went to masquerades, they could not more 
effectually relieve the insipidity of such amusements and 
attract the attention of the demoiselles, than by appearing 
at the supper table with a mask of this construction, and 
serving themselves by its assistance. It would be difficult, 
to be sure, by mechanism to supply the place of the mus- 



128 STATES OF INSECTS. 

cles with which in the insect it is amply provided : but 
Merlin, or his successor, has surmounted greater obsta- 
cles. In the larva of the Fabrician JEshiice {Libellula 
grandis, &c. L.), this apparatus is not convex but flat : 
so that, though it equally conceals the face, it does not so 
accurately resemble a mask ; and the jaws at its apex are 
not convex plates, but rather two single conical teeth a . 
It is, as to its general shape, similarly constructed in 
Agrion Fab. [L. Virgo, &c. L.); but the first joint is 
more remarkably elongated, the jaws more precisely re- 
semble jaws than in any of the rest, and are armed with 
three long, very sharp teeth : between them also there is 
a lozenge-shaped opening, through which, when the ap- 
paratus is closed, is protruded a circular sort of nipple, 
apparently analogous to the ligula b . Libellula amea, L., 
which is the type of another tribe (Cordulia Leach), has 
a mask somewhat different from all the above, the jaws be- 
ing armed with a moveable claw and an internal tooth c . 
You will admire the wisdom of this admirable contri- 
vance, when you reflect that these larvae are not fitted to 
pursue their prey with rapidity, like most predaceous 
animals ; but that they steal upon them, as De Geer ob- 
serves d , as a cat does upon a bird, very slowly, and as if 
they counted their steps ; and then, by a sudden evolu- 
tion of this machine, take them as it were by surprise, 
when they think themselves safe. De Geer says, it is 
very difficult for other insects to elude their attacks, and 
that he has even seen them devour very small fishes e . 

a Reaum. vi. t. xxxvii./. 4 — 6. 8. 

b Ibid. t. xxxviii. First joint/. 8. bfp. ; jaws/. 7. c d.; opening o, 
Ligula/. 6. /. 

e De Geer ii./. 17, Jaws gg; claw d; tooth h. d Ibid. 674. 
e Ibid. ii. G74. 



STATES OF INSECTS. 129 

As these animals are found in almost every ditch, you 
will doubtless lose no time in examining for yourself an 
instance of so singular a construction. 

Feelers (Palpi). In the orders Diptera and Hymeno- 
ptera are many larvae in which these organs have not 
been certainly discovered; yet Reaumur in that of a com- 
mon fly [M. meridiana L.) found four retractile nipples a 
which seem analogous to them; and Latreille has ob- 
served, that below the mandibles of those of ants are 
four minute points, two on each side b : but in all other 
larvae their existence is more clearly ascertained. The 
maxillary palpi vary in number, many having two on 
each maxilla and others only one. In the perfect insect 
the former is one of the distinguishing characters of the 
predaceous beetles (Entomophagi Latr.), but in the larvae 
it is more widely extended; since even in the caterpillars 
of Lepidoptera the inner lobe of the maxilla which re- 
presents this feeler is jointed, which is precisely the case 
with the beetles just named. Cuvier has observed this 
circumstance in the larva of the stag-beetle c ; and it be- 
longs to many other Coleopiera that have only a pair of 
maxillary palpi in the perfect state. The labial palpi are 
always two, emerging usually one on each side from the 
apex of the under-lip. With regard to the form of the 
palpi, those of the Lepidoptera are mostly conical ; in 
other orders they are sometimes setaceous and some- 
times filiform. Their termination is generally simple, 
but sometimes the last joint is divided. They are for the 
most part very short, and the labial shorter than the 

a Reaum. iv. 376. b N. Diet. d'Hist. Nat. xii. 64. 

c Anat. Comp. iii. 322. 
VOL. III. K 



130 STATES OF INSECTS. 

maxillary. The latter never exceed four joints % which 
seems the most natural number; and the former are limit- 
ed to three. Both vary between these numbers, and one 
joint. The joints, though commonly simple, are sometimes 
branched. This is the case with one I met with in con- 
siderable numbers upon the Turnip, in October 1808, 
the second joint of the palpi of which sends forth near 
the apex an internal branch. In the larva of the Cossus, 
as Lyonnet informs us b , the joints of the palpi are re- 
tractile, so that the whole of the organ may be nearly 
withdrawn. 

After thus describing the head of larvae, and its prin- 
cipal organs, we must next say something upon the re- 
mainder of the body, or what constitutes the 

2. Trunk and Abdomen : which I shall consider under 
one article. These are composed of several segments or 
rings, to which the feet and other appendages of the 
body are fixed. The form of these segments, or that of 
their vertical section, varies considerably: in many Lepi- 
doptera, the wire-worm, &c, it would be nearly circular; 
in others a greater or less segment of a circle would re- 
present it ; and in some, perhaps, it would consist of two 
such segments applied together. Their lower surface is 
generally nearly plane. Their most natural number, 
without the head and including the anal segment, is 
twelve: this they seldom excee v d, and perhaps never 
fourteen. The three first segments are those which re- 

a At first in the Bytisci they appear to have five joints ; but, as I 
before observed, the first joint must be regarded as representing the 
maxilla. 

b Lyonnet Anatom. 55, 58. 



STATES OF INSECTS. 131 

present the trunk of the perfect insect, and to which the 
six anterior legs when present are affixed. In general, 
they differ from the remaining segments only in being 
shorter, and in many cases less distinctly characterized; 
but in Neuropterous larvae, those of Dytisci, and some 
other Coleoptera, they are longer than the succeeding 
ones, and pretty nearly resemble the trunk of the animal 
in its last state. The surface of the trunk and abdomen 
will be considered under a subsequent head ; I shall not, 
therefore, describe it here. The conformation of the dif- 
ferent segments varies but little, except of the terminal 
one, or tail, which in different larvae takes various figures. 
In most, this part is obtuse and rounded; in others acute 
or acuminate ; in others truncate ; and in others emargi- 
nate, or with a wider sinus, and with intermediate modifi- 
cations of shape which it would be endless to particularize. 
In some, also, it is simple and unarmed ; in others be- 
set with horns* spines, radii, and tubercles of different 
forms, some of which will come under future considera- 
tion. The parts connected with the trunk and abdo- 
men which will require separate consideration, are the 
legs, the spiracles, and various appendages. 

Legs. It may be stated generally that the larvae of the 
orders Coleoptera, Lepidoptfra, and Neuroptera, have 
legs ; and that those of the orders Uymenoptera and Di- 
ptera have none. This must be understood, however, 
with some exceptions. Thus the larvae of some Coleo- 
ptera, as the weevil tribes (Curculio L.) have no legs, un- 
less we may call by that name certain fleshy tubercles be- 
smeared with gluten, which assist them in their motions a ; 

a De Geer v. 203; 

K 2 



132 STATES OF INSECTS. 

while those of Tcnlhredo and Sirex in the order Hymm- 
optera are furnished with these organs. At present I 
know no Dipterous larva that may be said to have real 
leo-s, unless we are to regard as such certain tentacula 
formed upon a different model from the legs of other lar- 
vae a . Rosel has, I think, figured a Lepidopterous apode* 
No Neuropterous one has yet been discovered. 

The legs of larvae are of two kinds \ either horny and 
composed of joints, or fleshy and without joints b . The 
first of these, as I observed in a former letter c , are the 
principal instruments of locomotion, and the last are to 
be regarded chiefly as props and stays by which the ani- 
mal keeps its long body from trailing, or by which it 
takes hold of surfaces ; while the other legs, or where 
there are none, the annuli of its body, regulate its mo- 
tions. The former have been commonly called true legs 
{pedes veri), because they are persistent, being found in 
the perfect insect as well as in the larva ; and the latter 
spurious legs (pedes spurii), because they are caducous, 
being found in the larva only. Instead of these not very 
appropriate names, I shall employ for the former the 
simple term legs, and for the latter prolegs (propedes) d . 
.."The. legs, when present, are always in number six, and 
attached by pairs to the underside of the three first seg- 
ments of the trunk. They are of a horny substance, and 
consist usually of the same parts as those of the perfect 

a De Geer iv. 5. Legs of this kind are figured Plate XXIII. 
Fig. 7. 

b In the larva, however, of Sialis, or some kindred genus, in which, 
like those of Scolopendra, the prolegs are jointed, a pair distinguishes 
each abdominal segment. See Reaum. iv. t. xv.f. I, 2. Compare De 
Geer ii. t. xxiii./. 11. 

c See above, Vol. II. 28G— . <i Ibid. 288. 



STATES OF INSECTS. 133 

insect; namely, coxa, trochanter, femur, tibia, and tarsus, 
suspended to each other by membranous ligaments: these 
parts are less distinctly marked in some than in others. 
Thus in the legs of a caterpillar, or the grub of a capri- 
corn-beetle, at first you would think there were only three 
or four joints besides the claw; but upon a nearer inspec- 
tion, you would discover at the base of the leg the rudi- 
ments of two others a , in the latter represented indeed by 
the fleshy protuberance from which the legs emerge. 
In the larvae of the predaceous Coleoptera, the hip and 
trochanter are as conspicuous nearly as in the perfect 
insect; and the tarsus, which still consists of only a sin- 
gle joint, is armed with two claws b . In those of the 
Neuroptera order, in which all the joints are very con- 
spicuous, the tarsi are jointed, as well as two-clawed c . 
The legs of larvae are usually shorter than those of the 
perfect insect, and scarcely differ from each other in 
shape, for they all gradually decrease in diameter from 
the base to the apex. This is the most usual conforma- 
tion of them in Lepidopterous, Hymenopterous, and 
some Coleopterous larvae, (those of the capricorn-beetles 
are very short and minute, so as to be scarcely visible,) 
in which they are so small as to be concealed by the body 
of the insect d . In Neuropterous larvae, however, and 

? Lyonnet Anatom. t. uuf. 8. Coxan. Trochanter c. Femur d. Ti- 
bia e. Tarsus f. Claw g. 

b De Geer iv. t. xiii./. 20; and t. xv./. 16. 

c Ibid. ii. t. xvi./. 5, 6, 7- d e: and t. xix./. 4. efg h. 

d The larva of a scarce moth (Stauropus Fagi. See Plate XIX. 
Fig. 4) is an exception to this. The first pair of its legs are of the 
ordinary stature, but the two next are remarkably long, and so thin 
and weak as to be unable to bear the body. Pezold. 119. Another 
minute caterpillar described by Reaumur has the third pair of the 



134- STATES OF INSECTS. 



several Coleoptera, as those of Dytiscus, Staphylinus, Coc- 
cinella, &c., they more resemble the legs of the perfect 
insect, the joints being more elongated, and the femoral 
one projecting beyond the body a . 

You will find no other than true legs in most Coleo- 
pterous, Neuropterous, and Hymenopterous larvae. But 
those of the saw-flies ( Tenthredo L.), and all caterpillars, 
have besides a number of prolegs : a few Dipterous larvse 
also, are provided with some organs nearly analogous to 
them. These prolegs are fleshy, commonly conical or 
cylindrical, and sometimes retractile protuberances, usu- 
ally attached by pairs to the underside of that part of 
the body that represents the abdomen of the future fly b . 
They vary in conformation and in number; some having 
but one, others as many as eighteen. 

With regard to their conformation, they may be di- 
vided into two principal sections: first, those furnished 
with terminal claws; and secondly, those deprived of 
them. Each of which may be divided into smaller sec- 
tions, founded on the general figure of the prolegs, and 
arrangement of the claws or hooks. 

legs apparently fleshy and singularly incrassated at the apex into a 
pyriform figure, terminated by a pair of claws. This conformation 
is for some particular purpose in the economy of the animal, since 
they are the most busily employed of all in arranging the threads of 
her web. Reaunj. ii. 258. In the larva of a geometer (Geometfa lu- 
lutna) the third pair are remarkably long. Illig. Mag. 402. In that 
of another moth, according to Kuhn (Naturf. xvi. 78. t. iv./. 3), the 
third pair of the fore-legs is remarkably incrassated, being twice as 
thick and long as the other pair, though consisting of the same num- 
ber of joints, the last of which has claws. 

a On the legs and prolegs see also what is said above, Vol II 
p. 286'—. 

b In some few instances these legs are dorsal. Ibid. 281. 



STATES OF INSECTS. 135 

i. The prologs of almost all Lepidopterous larvae are 
furnished with a set of minute slender horny hooks, crot- 
chets, or claws, of different lengths, somewhat resem- 
bling fish-hooks ; which either partially or wholly sur- 
round the apex like a pallisade. By means of these 
claws, of which there are from forty to sixty in each 
proleg, a short and a long one arranged alternately, the 
insect is enabled to cling to smooth surfaces, to grasp 
the smallest twigs to which the legs could not possibly 
adhere : a circumstance which the flexible nature of 
the prolegs greatly facilitates a . Claws nearly similar 
are found on the prolegs of some Dipterous larva? b , but 
not in any of those of the other orders. These last, how- 
ever, are seldom either so numerous, or arranged in 
the same manner, as in caterpillars. When the sole of 
the foot is open, the claws with which it is more or less 
surrounded are turned outwards, and are in a situation 
to lay hold of any surface ; but when the animal wishes 
to let go its hold, it begins to draw in the skin of the sole, 

a The claws or crotchets, though general, are not universal, in 
Lepidopterous larva?. An exception is furnished to the rule by the 
singular limaciform ones of Hepialus Testudo and Asellus of Fabricius, 
two moths forming Haworth's genus Apoda, which have no distinct 
prolegs, but in their stead a number of small transparent shining tu- 
bercles without claws. The larva also of one of the subcutaneous 
moths first discovered by De Geer in the leaves of the rose (i. 446), 
but whose history is fully given by Goeze, Naturf. xv. 37 — 48, (who 
has satisfactorily ascertained that it is the true larva of a Tinea of 
Linne, but of a different habit from that of most subcutaneous ones), 
has no true legs, and eighteen prolegs without any claws. Another 
subcutaneous larva, for the history of which we are indebted to 
M. Godeheu de Riville, is according to him entirely deprived of legs 
of any kind (Bonnet ix. 196 — .); as is another of the same tribe that 
feeds on the poplar, an account of which is given by Goeze Naturf, 
xiv. 105. b Plate XXIV, Fig. 7. See also below, p. 137- 



136 STATES OF INSECTS. 

and in proportion as this is retracted, the claws turn 
their points inwards, so as not to impede its motion a . 

The prolegs with claws may be further divided into 
four different kinds. 

1. In the larvae of the great majority of butterflies 
and moths they assume the form of a truncated cone, 
the lower and smaller end of which is expanded into a 
semicircular or subtriangular plate, having the inner 
half of its circumference beset with the claws above men- 
tioned ; and, from its great power of dilating and con- 
tracting, admirably adapted for performing the offices of 
a foot. Jungius calls these ]egs pedes elephantini b ', and 
the term is not altogether inapplicable, since they exhibit 
considerable resemblance to the clumsy but accommo- 
dating lee; and foot of the gigantic animal he alludes to. 

2. The larvas of many minute moths, particularly of 
the Fabrician genera Tortrix and Tinea — those which 
live in convoluted leaves, the interior of fruits, &c, as well 
as the Cossits, and Some other large moths, — have their 
prolegs of a form not very unlike those of the preceding 
class, but shorter, and without any terminal expansion ; 
the apex, moreover, is wholly, instead of half, surround- 
ed with claws c ; the additional provision of which, to- 
gether with a centrical kind of nipple capable of being 
protruded or retracted, in some measure, though imper- 
fectly, supplies the place of the more flexible plate-like 
expansion present in the first class. 

3. The third class is composed of a very few Lepido- 
pterous larvae which have their prolegs very thick and 
conical at the base, but afterwards remarkably slender, 

a Lyonnet Anatom. 84. t. iu.f, 11, 12. 

b Hist. Vcrmium, 3 30. c p LATi: XXIII. Fig. 1. 



STATES OF INSECTS. 137 

long, and cylindrical, so as exactly to assume the shape 
of a wooden leg a . These, as in the first class, are ex- 
panded at the end into a flat plate : but this is wholly cir- 
cular, is surrounded with claws, and has also in the mid- 
dle a retractile nipple, as in the preceding class. In 
Cossus, at least in an American species (Cossus Robinia:), 
described by Professor Peck b , the anal prolegs have the 
claws only on their exterior half. 

4. The remaining description of unguiferous prolegs, 
if they may not rather be deemed a kind of tentacula, 
are those of certain Diptera, provided with no true legs ; 
which differ from the three preceding classes, either in 
their shape, or the arrangement of their claws. In 
one kind of those remarkable larvae, which from their 
long respiratory anal tubes Reaumur denominates " rati 
tailed" that of Elophilus pendulus, there are fourteen of 
these prolegs, affixed by pairs to the ventral segments, 
the twelve posterior ones of which are subcorneal, and 
truncate at the apex, which is surrounded with two cir- 
cles of very minute claws, those of the inner being much 
more numerous and shorter than those of the exterior 
circle ; while the anterior pair terminate in a flat expan- 
sion, and in shape almost exactly resemble those of a mole c . 
The prolegs of the larvae of a kind of gnat called by 
De Geer Tipida amphibia^ and of Syrphus mystaeeus F., 
(Masca plumata De Geer,) are nearly of a similar con- 
struction, but in the last are armed with three claws 
only d . Long moveable claws also distinguish the sin-. 

a Plate XXIII. Fig, 17. 

b Account of Locitst-tree Insect, 1 ;, 69. 

c Reaum. iv. 443. t. xxx.f. G. II. I. xxii./. C. / /. 

d Dc Geer vi. 383. and 137. /, viii./. 8, 9. 



138 STATES OF INSECTS. 

gular prolegs before described a of another gnat ( Tany- 
pus maculatus Meig., Tipula De Geer). The case-worms 
(Trichopiera K.) and some others, have two prolegs at 
the anus, each furnished with a single claw b . 

ii. The prolegs deprived of claws are found in the 
larva of the Hymenopterous tribe of saw-flies ( Tenthredo 
L.), in those of some Lepidoptera (Hepialus F. &c), and 
in some few Coleopterous and Dipterous genera. Those 
of the former are of the shape of a truncated cone, and 
resemble the second class of unguiculate prolegs, except 
in the defect of claws. In the latter they are a mere re- 
tractile nipple-like protuberance, in some species so small 
as scarcely to be perceptible. In all they aid in progres- 
sive motion ; but it is by laying hold of surfaces, and so 
enabling the body more readily to push itself forward by 
annular contraction and dilatation, and not by taking 
steps, of which all prolegs are incapable : to assist in this 
purpose the protuberance sometimes secretes a gluten c , 
which supplies the place of claws. Some larvae have the 
power of voluntarily dilating certain portions of the un- 
derside of their body, so as to assume nearly the shape 
and to perform the functions of prolegs. In a Coleopte- 
rous (?) subcortical one from Brazil, before alluded to, 
there are four round and nearly flat areas in each ventral 
segment of the abdomen, but the last very little raised 
above the surface, and rough, somewhat like a file; and 
besides these, the base of the anal segment has ten of 
these little rough spaces, but of a different shape, being 
nearly linear, placed in a double series, five on each side. 
Doubtless these may be regarded as a kind of prolegs^ 

" See above, Vol. II. p. 278. Dc Geer ubi supr. 376. 

! ' Rcaura. iv, 181. t, xv, f, 12, c c. c De Geer v. 203. 



STATES OF INSECTS. 139 

which enable the animal to push itself along between the 
bark and the wood a . 

In considering, in the next place, the number and si- 
tuation of the prolegs, it will contribute to distinctness to 
advert to these circumstances as they occur in the diffe- 
rent orders furnished with these organs. 

To begin with the Lepidoptera. — Lepidopterous larvae 
have either ten, eight, six, or two prolegs, seldom more b , 
and never fewer. Of these, with a very few exceptions, 
two are attached to the last or anal, and the rest, when 
present, to one or more of the sixth, seventh, eighth, and 
ninth segments of the body : none are ever found on the 
fourth, fifth, tenth, or eleventh segments. 

1. Where ten prolegs are present, as is the case in by 
far the greatest proportion of Lepidopterous larva?, there 
is constantly an anal pair, and a pair on each of the four 
intermediate segments just mentioned. 

2. In caterpillars, which like those of a few species of 
the genera Sphinx, Pyralis, and of the Bombycidce, &c. 
have eight legs, -they are placed in three different ways. In 
those which have an anal pair, the remaining six are in 
some fixed to the sixth, seventh, and eighth ; in others, to 
the seventh, eighth, and ninth segments. In those which, 
like Cerntra Vinula, and several other species of the 
same family, have no anal prolegs; the whole eight 
emerge from the sixth, seventh, eighth, and ninth seg- 
ments. 

3. The Hemigeometers, as Noclua Gamma, &c. have 

a See above, p. 110, 114. 

b Some few subcutaneous larvae have more, as that, before men- 
tioned, observed by Dc Geer in the leaves of the rose ; which has 
eighteen prolegs, and no true ones. 



HO STATES OF INSECTS. 

only six legs : namely, an anal pair, and two ventral ones, 
situated on the eighth and ninth segments. 

4. The larvae of the Geometers (Geomctrcc F.) have 
butyb^- prolegs ; of which two are anal, and two spring 
from the ninth segment. It should be observed, how- 
ever, that the larvae of Hemigeometers, and even of some 
of those that have ten prolegs, where the four anterior ones 
are much shorter than the rest, move in the same way as 
the Geometers. This even prevails in a few where these 
organs are all of equal length. 

5. Many of the larvae of Tinea L. which live in the in- 
terior of fruits, seeds, &c, have but one pair of prolegs, 
which are attached to the anal segment. 

6. The larvae of Haworth's genus Apoda (Hepialus 
Testudo and Asellus F.), remarkable for their slug-like 
shape and appearance, move by the aid of two lateral 
longitudinal pustule-like protuberances, which leave a 
trace of a gummy slime in their course. 

Hymenoptera. — The larvae of the different tribes of 
Tenthredo L., almost the only Hymenopterous insects in 
which prolegs are present, have a variable number of these 
organs ; some sixteen, as the saw-fly of the willow ( T. lu- 
tea L.), and this is the most numerous tribe of them, in- 
cluding the modern genera, Cimbex F., Pterophdrus, &c. 
Others have fourteen, as that of the cherry ( T. cerasi L.); 
and many others with only nine joints to their antennae. 
A third class have only twelve, as that of the rose ( T. Ro- 
sce L.), but this contains but few species. The last class 
contains those that have no prolegs at all, but only the six 
horny ones appended to the trunk. Of this tribe, the 
caterpillars of which have a very different aspect from 
the preceding, are those of the genus Lyda F, ( 11 cry- 



STATES OF INSECTS. 141 

throcephala L.) a . Two of the prolegs are anal, and the 
rest intermediate, and none are furnished with claws; 
This circumstance, in conjunction with the greater num- 
ber of prolegs, except in the case of Lyda, will always 
serve as a mark to distinguish these fausses chenilles, as 
the French call the larvae of saw-flies, from true caterpil- 
lars. The dorsal prolegs of a species of Cynips described 
by Reaumur have been before noticed. 

Coleoptera. — The larva? of insects of this order are so 
little known or attended to, that no very accurate gene- 
ralization of them in this respect is practicable. Many of 
them, in addition to their six horny legs, have a proleg 
at the anus ; which in many cases appears to be the last 
segment of the abdomen, forming an obtuse angle with 
the remainder of it, so as to support that part of the body, 
and prevent it from trailing; and in some instances, as 
in Chrysomela Popidi, a common beetle, secreting a slimy 
matter to fix itself 5 . In the larvae of Staphylinidce this 
proleg is very long and cylindrical j in that of Cicin- 
dela it is shorter, and in shape a truncated cone rather 
compressed ; it is very short, also, in those of the Silphce 
that I have seen. In the wire-worm (Elater Segetum) it 
is a minute retractile tubercle, placed in a nearly semi- 
circular space, shut in by the last dorsal segment, which 
becomes also ventral at the anus. This space is in fact 

a De Geer ii. t. xhf. 15, 16. Bergman has added to these four 
classes of the larva? of saw-flies, a fifth ; the insects belonging to 
which, he affirms, though they have sixteen prolegs, are without the 
anal pair. Ibid. 931. But as neither De Geer nor Reaumur ever met 
with one of this description, it is probable he was mistaken. Reaumur 
thought he had seen one with eighteen prolegs upon Erysimum alli- 
aria (v. 91), but he does not speak positively. 

b De Geer v. 288. 



142 STATES OF INSECTS. 

i 

the last ventral segment. This seems characteristic of 
the genus a . From the underside of the body of the 
common meal-worm ( Tenebrio Molitor), at the junction 
of the two last segments, when the animal walks, there 
issues a fleshy part, furnished below with two rather hard, 
long, and moveable pediform pieces, which the animal 
uses in walking b . In the larva of another beetle, whose 
ravages have been before noticed, under the name of the 
cadelle c ( Trogosita mauritanica\ a pair of prolegs are 
said to be found under the anal segment ; and in that of 
the bloody-nose beetle {Timarcha tenebricosa\ that seg- 
ment is bifid. That of the weevil of the common water- 
hemlock (Lixus paraplecticiis F.) exhibits a singular ano- 
maly: prolegs occupy the usual station of the true legs, 
being attached to the three segments representing the 
trunk d . This insect, however, does not appear to use 
them in moving. A pair in each of the twelve segments 
of the body are found in the grub of another weevil 
(Hypera Rumicis Germ.), the nine last pair being the 
shortest, which all assist the insect in walking e . But the 
greatest number of prolegs is to be found in the Brazil 
subcortical larva lately mentioned. Besides the six horny 
legs of the trunk, this remarkable animal has four pro- 
legs on each of the seven intermediate abdominal seg- 
ments, and five on each side of the base of the last, 
making the whole number of prolegs, if so they may 
be called, amount to forty-four: a far greater number 
than is to be found in any larva at present known. When 
I wrote to you upon the motions of insects, I informed 

a De Geer iv. 157. b Ibid. v. 36. t. u.f. 11. 

c See above, Vol, I. p. 171. a De Geer v 228 

e Ibid. 233. 



STATES OF INSECTS. 143 

you that some larvae moved by means of legs upon their 
back a , but I was not then aware that any were furnished 
with them both on the back and the belly at the same 
time. By the kindness of Mr. Joseph Sparshall of Nor- 
wich, a very ardent and indefatigable entomologist, I am 
in possession of the larva of Rhagiumfasciatum, a timber- 
feeding beetle. This animal on the ten intermediate seg- 
ments of the underside of the body, which in the centre 
form a fleshy protuberance, has oh it a double series of 
rasps, as it were, consisting each of two rows of oblique 
oblong prominences ; and on the seven intermediate dor- 
sal segments there are also in the centre seven rasps of 
three or four rows each, of similar prominences : so that 
this animal at the same time can push itself along both by 
dorsal and ventral prolegs. It is worthy of observation, 
that a pair of these rasps is between the second and third 
pair of true legs. 

Diptera. — The larva of a little gnat, Tipula stercora- 
ria De Geer b (ChironomusM.eig.?), drags itself along by 
the assistance of a single tubercle, placed on the under- 
side of the first segment of the body, which the animal 
has the power of lengthening or contracting c . That of 
another beautiful Chironomus (C. plumosus), remarkable 
for the feathered antennas of the male d , has two short 
prolegs, or pediform but not retractile tentacula in the 
same situation e . Others, as that of Tanypus maculatus, 

a See above, Vol. II. p. 281. b De Geer vi. 388. 

c Ibid. 389. d Reaum. v. t. \.f. 10. 

€ Ibid. 31. This larva has also a pair of pediform processes at the 
anus, surrounded at the end with claws (t. v./. 4, 5, s s), which he 
saw the animal use in locomotion ; but which he suspects to be re- 
spiratory organs (Ibid. 33), which Latreille asserts they are. Gen. 
Crust, et Ins, iv. 249. 



144 STATES OF INSECTS. 

&c. have two pairs, one attached to the anal and the 
other to the first segment a . Tipula amphibia De Geer 
in this state has ten prolegs, placed by pairs on the fourth, 
fifth, eighth, ninth, and tenth dorsal segments b ; and 
Scceva Pyrastri F., one of the aphidivorous flies, has not 
fewer than forty-two, arranged in a sextuple series, seven 
in each row c . 

It may not be useless to close this long description of 
the legs of larvae with a tabular view of them, founded 
chiefly upon these organs; which afford very obvious 
mai'ks of distinction. 

I. Larva} without legs. 

i. With a corneous head of determinate shape (co- 
leopterous and hymenopterous apods — Cidicidce, 
some Tipulidce, &c. amongst the Diptera). 

ii. With a membranaceous head of indeterminate 
shape (Muscidcs, Syrphida, and other Diptera). 

II. Larvae with legs. 

i. With legs only, and with or without an anal pro- 
leg (Neuroptera, and many Coleoptera). 

1. Joints short and conical (Elater, Cerambyci- 
d<z, &c). 

2. Joints long and subfiliform (Staphylinus, 
Coccinella, Cicindela, &c). 

ii. Prolegs only (many Tipulidce, and some subcu- 
taneous Lepidopterous larvae, &c). 

iii. Both legs and prolegs {Lepidoptera, Tenthredi- 
nidce, and some Coleoptera). 

1. Without claws {Tenthredinidae, &c). 

2. With claws {Lepidoptera, &c). 

a De Geer Ibid. /. xxiv.f. 15 — 17. >> Ibid. 383. 

e Ibid. 111. t.\i.f. 14— 1G. 



STATES OF INSECTS. 145 

I should next say something upon the spiracles, or 
breathing-pores, or any other external apparatus for the 
purpose of respiration, in larvae ; but I think it will be 
best to reserve the consideration of these for a subsequent 
Letter. We will therefore conclude this detailed de- 
scription of their parts in their first state, with some ac- 
count of their other 

iii. Appendages. The generality of larvae have no other 
external organs than those already described ; but in se- 
veral of them we observe various kinds of retractile ones 
and others — protuberances — horn-like processes — rays, 
&c. ; which, though not properly coming either under 
any of the above parts, or under the clothing of these 
animals, yet require to be noticed. Upon these I shall 
now enlarge a little. 

You must have observed upon the back of the last seg- 
ment but one of the caterpillar of the silk- worm a horn- 
like process, rising at first nearly perpendicularly, and 
then bending forward. A similar horn, though confined 
in the genus Bombyx to the silk-worm and a few others, 
if we may believe Madame Merian, who, however, often 
makes great mistakes, is found in the beautiful caterpillar 
of one of the largest and finest moths that we know 
(Erebus Stria: a ), the glory of the Noctuidce, and in most 
of those of the hawk-moths (Sphinx F.) [$. Porcellus, Vi- 
tis, and a few others excepted; in some of which, as 
S. Labruscce, &c, this anal horn is replaced by a gibbo- 
sity, and in others, as S. (Enotherce, by a callous eye-like 
plate b ] in the same situation, but much longer c , and 

a Merian Ins. Sur. t. xx. b Ibid. t. xxxiv. 

c I have a caterpillar, I believe from Georgia, in which this horn 
is nearly an inch long, filiform, slender, and tortuous. 
VOL. III. L 



146 STATES OF INSECTS. 

commonly curving backwards over the tail 3 . Some- 
times, however, as in S. ocellata and S. Stellatarum, it is 
perfectly straight. These organs towards the apex are 
horny, and often end in a sharp point ; nearer the base 
they are fleshy. They are without any true joint b , yet 
the insect can elevate or depress them at pleasure. Un- 
der a lens, they usually appear covered with spinous emi- 
nences, arranged like scales. The use of these horns is 
quite unknown : Goedart fancies that they secrete a po- 
tent poison, and are intended as instruments of defence; 
but both suppositions are altogether unfounded. It has 
been remarked, that the body of those caterpillars which 
have these horns, is firmer, and yields less to the touch 
than that of those which have no such appendages c . The 
larva of a small timber-devouring beetle {Lymexylon der- 
mestoidesF.) has, like the above caterpillars, a long horn, 
and in the same situation : it has also a singular protu- 
berance on the first segment d . Upon some other cater- 
pillars, as mBombyx Stigma F., a singular pair of horn-like 
appendages arises from the back of the second segment of 
the body, excluding the head. In a tawny-coloured one 
from Georgia, with a transverse row of short black spines 
on each segment, these horns are half an inch long, 
black, covered with spinous eminences, rather thickest at 
the base, and terminate in a little knob. They appear to 
articulate with the body at the lower extremity. I have 
another species, black, with narrow longitudinal yellow 

a Plate XVIII. Fig. 12. c. 

b That of Sphinx latrophce L. appears to be jointed, at least it is 
moniliform. Merian Surinam, t. xxxviii. Compare also t. iii. 
N, Diet. d'Hist. Nat. vi. 252. 
d Schellenberg Entomolog. Beytr. t. 1. 



STATES OF INSECTS. 147 

stripes, in which these horns are of equal thickness at 
base and apex, but with the same terminal knob. Da- 
nais Archippus has a pair of tentacula at the head, and 
another pair, but shorter, at the tail ; and D. Gylippus 
has, besides these, two in the middle of the body a . 

We are equally ignorant of the use of the upright horn 
found upon the back of the fourth segment in the larva of 
some moths (Noctua Psi, and tridens F.) which is of a con- 
struction quite different from that of those last described. 
It is cylindrical, slightly thinner at the apex, which is 
obtuse, fleshy, incapable of motion, of a black colour, and 
about two lines long. On the same segment, also, in the 
case-worms ( Trichoptera K.) are three .fleshy conical emit 
nences, which the animal can inflate or depress, so that 
they sometimes totally disappear, and then in an instant 
swell out again. When retracted, they form a tunnel- 
shaped cavity, varying in depth b . Reaumur conjectured 
that these eminences were connected with respiration, 
and one circumstance seems in favour of this conjecture, 
that this segment has not the respiratory threads observ- 
able in the subsequent ones. Latreille mentions certain 
fleshy naked eminences placed upon the ninth and tenth 
segments of some hairy caterpillars, which, like those just 
mentioned, the animal can elevate more or less. They 
are often little cones ; but when it would shorten them, 
the summit is drawn in, and a tunnel appears where be- 
fore there was a pyramid c . 

In a former Letter I gave you a short account of the 

a Smith's Abbott's hisects of Georgia, t. xiii. 
b De Geer ii. 507. t. x\.f. 16. m n. t. xiv./. 7- 
c N. Diet, a" Hist. Nat. vi. 256. 

L 2 



148 STATES OF INSECTS. 

remarkable Y-shaped, as it should seem, scent-organs 
(Osmateria) of the beautiful caterpillar of the swallow- 
tailed butterfly (Papilio Machaon L.), and others of the 
Equites a ; I will now speak of them more fully. That 
found in the former is situated at the anterior margin at 
the back of the first segment, close to the head, from 
which at first view it seems to proceed. At the bottom 
it is simple, but divides towards the middle, like the let- 
ter Y, into two forks, of a fleshy substance b , which it can 
lengthen, as a snail does its horns, to five times their or- 
dinary extent, or retract them within the stalk, so as wholly 
to conceal them. Sometimes it protrudes one fork, keep- 
ing the other retracted ; and often withdraws the whole 
apparatus for hours together under the skin, and its 
place is only marked by two tawny-coloured dots," so that 
an ordinary spectator would not suspect the existence of 
such an instrument c . Unfortunately this larva is rare 
in this country, so that I can scarcely flatter you with the 
hope of seeing this curious organ in a living specimen d , 
unless you choose to import a parcel of its eggs from the 
south of Europe, where it is common. This you will 
think rather a wild proposition ; but why should not En- 
tomologists import the eggs of rare insects, as well as bo- 
tanists the seeds of rare plants? But if you will be satis- 
fied with the dissection of a dead specimen, I have seve- 

a See above, Vol. II. p. 244 — . 

b Plate XIX. Fig. 1. a. 

c Reaum. i. t. xxx./. 2. N. Diet. d'Hist. Nat. xxiv. 490, 497—. 

d Ray says he found it feeding on common fennel, about Middle- 
ton in Yorkshire : Lett. 69. The indefatigable Mr. Dale recently 
found many in the neighbourhood of Whittlesea-mere, feeding on 
Selinum palustre. It will also eat the wild carrot. 



STATES OF INSECTS. 149 

ral, done by the ingenious Mr. Abbott of Georgia, in 
which this part is well exhibited a . 

Another small caterpillar, as it should seem, of a geo- 
meter, prepared by the same gentleman, exhibits a pair 
of similar horns on the fifth and sixth segments : in these 
the common base from which the fork proceeds is very 
short and wide, and each branch grows gradually more 
slender from the base to the apex, where it is involute. 
Whether these are retractile, or whether they correspond 
with those of P. Machaon in their nature and use, cannot 
be ascertained from a dead specimen : as they belong to a 
larva of a quite different tribe of Lepidoptera, the proba- 
bility is, that they essentially differ. Two globose re- 
tractile vesicles issue from the ninth and tenth segments 
of those of Arctia chrysorrhea, &c. b 

A great number of Lepidopterous larvae, particularly 
those which are smooth and of a moderate size, have be- 
tween the under-lip and fore-legs a slender transverse open- 
ing, containing a teat-like protuberance of the same con- 
struction as the furcate horn of the caterpillar of the beau- 
tiful mountain-butterfly, Parnassius Apollo ; and, like that, 
can either be wholly retracted and concealed, or by pres- 
sure be extended to the length of one of the legs. In some 
larvae this part is of a subhemispherical figure, generally 
single, but sometimes double. It is commonly, however, 
more slender and conical ; and when of this shape, it is 
sometimes quadruple c . The use of this part is not very 
clearly known : some have supposed it to be a second 
spinneret, and to be of use in fabricating the cocoon ; but 

* This gentleman was remarkable for the admirable manner in 
which he prepared caterpillars, so as scarcely to differ from life, 
b Reaum. i. 92, c Bonnet ii. 84—, iii. 1, 



150 STATES OF INSECTS. 

it is more probable that it secretes some other kind of 
fluid, and is connected with defence. 

The singular organ in a similar situation, evidently 
for that purpose, with which the puss-moth endeavours 
to annoy its assailants, has been described in a former 
Letter, to which I refer you a . Bonnet, who was the first 
that discovered this organ, ascertained that it might be 
cut off without injury to either larva or imago. He also 
remarked in a caterpillar found in the wild succory (Ci- 
chorium Intybus) another short, black, needle-shaped or- 
gan between the conical part just described and the un- 
der-lip b . De Geer mentions a remarkable fleshy horn- 
like style, which issues from the lower side of the first 
segment, between the head and the legs of the case-worms 
(Trichoptera) : he does not describe it as retractile, or it 
might be regarded as analogous to those of Lepidoptera 
similarly situated, that I have just noticed c . In that of 
the emperor-moth (Saturnia Pavonia\ there are perfo- 
rated tubercles, which when the animal is molested spirt 
forth a transparent fluid d . 

The horn-like appendage of the puss-moth (Centra Vi- 
nula) is situated at the tail of the insect, and is composed 
of two distinct cylindrical diverging branches, each about 
four lines long, not united at the base. Each of these is 
hollow, and includes a smaller cylindrical piece, which 
can be protruded at pleasure, and withdrawn again, as a 
pencil within its case ; or, rather, as the horns of a snail. 
The two outer horns are tolerably firm, moveable at their 
base, and beset with black spines ; the interior tentacula 
are fleshy, moveable in every direction, and in full-grown 

* See above, Vol. II. 251—. »> Bonnet ii. 88. 

c De Geer ii. 507- 1. xi./. 16. c. * Ros. iv. 162. 



STATES' OF INSECTS. 151 

larvae of a rose colour. The animal seldom protrudes 
them, unless in some way disturbed ; and frequently it 
approximates the two outer cases so closely that they re- 
semble a single horn. It appears to use these inner horns, 
when protruded, as a kind of whip to drive away the 
flies, especially the Ichneumons, that alight upon its body. 
When touched in any place, it will unsheath one of them, 
and sometimes both, and with them strike the place where 
it is incommoded a . A similar organ is found in some 
other Bombycidce, as B, Tau and Furcula F. Reaumur 
mentions a caterpillar that to this kind of tail added the 
resemblance of two ears, or two cylindrical bodies, ter- 
minating in a point, which emerged from the first segment 
behind the head b . In another observed by the same au- 
thor, the legs were replaced by a single horn, but which 
did not appear to send forth an internal one : from the 
back of its fourth segment also emerged a single conical 
or pyramidal fleshy eminence or cleft, terminating in two 
points c . Some of the tropical butterflies also, as may be 
seen in the figures of Madame Merian, have two diver- 
ging anal horns instead of anal prolegs ; but it does not 
appear that they incase tentacula d . Wherever these 
caudal horns are found, the above prolegs are wanting e . 

a De Geer i. 322—. See Plate XIX. Fig. 2. a a. 
b Reaum. ii. 275. t. xxii./. 3. 
c Ibid. 276. t. xxii./. 4, 5. 

d Ins. Surinam, t. vii. Nymphalis Amphinome xxiii. Morpho Teu- 
cer t. xxxii. PapUio Cassice. 

e This is not, however, universally the case, for the caterpillar of a 
Geometer described by Reaumur (ii. 363. t. xxix./. 8.) (G. amatoria) 
has a pair of fleshy anal horns, terminating, it should seem from his 
figure, in a minute hook that the animal uses as a forceps; which has 
at the same time the anal legs, of which indeed these horns seem to 
be appendages. 



1 52 STATES OF INSECTS. 

Two conical anal horns also distinguish the caterpillar 
of one of the moths called Prominents, Notodonta ca- 
melina; but these are not terminal, but on the back of 
the last segment but one a . In that of another Bri- 
tish moth, N. ziczac F., there are three dorsal promi- 
nences, one near the anus, and two more in the middle b . 
Some Geometers (G. fuliginosa, &c.) have two erect 
horns on the eleventh segment, and others (G. syringaria, 
&c.) two recurved ones on the eighth c . I must not here 
omit to mention the curious hooks emerging from two tu- 
bercles on the back of the eighth segment of the ferocious 
larva of that beautiful tiger-beetle, the Cicindela campe- 
stris L., not uncommon on warm sunny banks. This ani- 
mal with incessant labour, as we are informed by M. Des- 
marets, digs a cylindrical burrow, to the enormous depth, 
the size of the animal considered, of eighteen inches. To 
effect this, it carries out small masses of earth upon its large 
concave head; and having often occasion to rest in ascend- 
ing this height, by means of these hooks d it fixes itself 
to the sides of its burrow, and, having finally arrived at its 
mouth, casts off its burthen. When these insects lie in 
wait for their prey, their head, probably in conjunction 
with the first segment of the body, accurately stops the 
mouth of the burrow, so as to form an exact level with 
the surrounding soil ; and thus careless insects, walking 
over it without perceiving the snare, are seized in a mo- 
ment and devoured e . 

Another kind of appendage, which is found in some 

a Sepp. iv. t. 1./. 6—8. 

b Plate XIX. Fig. 5. a b. Sepp. iv. t. xii./. 4—7. 
« Ros. iii. 69. -» Plate XVII. Fig. 13. v. 

* N, Diet. d'Hiii, Nat. vii. 95. 



STATES OF INSECTS. 153 

larvae, is the organ employed by them to carry the excre- 
ment ; with which, instead of letting it fall to the ground, 
they form a kind of umbrella to shelter and probably con- 
ceal them. All the tortoise-beetles (Cassida L.) have in- 
struments for this purpose, as well as an Indian genus 
{Imatidium Latr.) very nearly related to them. This in- 
strument is a kind of fork, half as long as the body, con- 
sisting of two branches, growing gradually smaller from 
the base to the summit, where they terminate in a very 
fine point, of a substance rather horny, and attached to 
the body near the anal orifice. They are armed on the 
outside with short spines, from the base for about a third 
of their length. When this fork, as it usually is, is laid 
parallel to the back, with its points towards the head, the 
anal aperture points the same way. When the animal 
walks, the fork points the other way, and is in the same 
line with the body, and the anus assumes a prone posi- 
tion a . 

The larvae of a genus of flies (Volucella GeofFr.) re- 
markable for inhabiting the nests of humble bees, are di- 
stinguished on their upper side by six long, diverging, 
pointed, membranous radii ; placed in a semicircle round 
the anus b : what the particular use of these organs may 
be, has not been conjectured. Another in my collection 
has only four upper radii, but below the anus are two 
fleshy filiform tentacula. One of a Tipulidan described 
by Reaumur, has also four upper teeth; but instead of 
two subanal tentacula, has six c . The singular larva of 
another of this tribe (Chironomm plumosus) has on the 

a De Geer v. 170- t. v.f. 19—23. Compare Reaum. iii. 235—. 
b Plate XIX. Fig. 11, a. De Geer vi. 137. Reaum. iv. 482. 
c Reaum. iv. t. xiv./. 9, 10. 



154? STATES OF INSECTS. 

two last segments four long, fleshy, filiform, flexible ten- 
tacula, often interlaced with each other ; which, accord- 
ing to the same illustrious author, are used by the ani- 
mal to fix its caudal extremity, like the geometers, that the 
other end may be at liberty. Besides these organs round 
the anus, it has also four other oval ones, of uncertain 
use : not to mention the two prolegs, which M. Latreille 
thinks are air-tubes a . Jointed anal organs are observ- 
able in other larvae : those in that of a saw-fly described 
by De Geer (Lyda F.) consist of three joints 5 ; in that 
of Hister cadaverinus, a carnivorous beetle, of two c . 
The larva as well as the pupa and imago of Ephemera 
is furnished with three long diverging multiarticulate 
tails, which are probably useful as a kind of rudder to 
assist and direct their motions. That of the smaller 
dragon flies (Agrion F.) is furnished with three long ver- 
tical laminae, by moving which, as fish do their tails, 
from side to side, the animal makes its way in the water d . 
That singular one, also, with a hooked head, figured by 
Reaumur, has a single swimming lamina, or fin, shaped 
like a fan, and placed in a vertical position under the 
tail e . 

The whole circumference of the body in some coleopte- 
rous larvae, — for instance, in that of the tortoise-beetle 
lately mentioned, — is surrounded with appendages like 
rays. These are sometimes simple, rough with very 
short spinous points f ; but I have a dipterous larva, in 

a Reaum. v. 32. t. v./. 3—5. Latr. Gen. Crust, et Ins. iv. 249. 

b De Geer ii. 1031. t. xlf. 13, 14. kk. 

c JV. Diet. eTHist. Nat.x. 430. 

d De Geer ii. 697. t. xxi./. 4, 5. b b b. 

e Reaum. v. t. vi.f. 7. n. 

1 Plate XVIII. Fig. 2. 



STATES OF INSECTS. 155 

which these radii themselves are beautifully pinnated by 
a fringe of longish spines on each side. Reaumur has de- 
scribed the grub of a beetle, the genus of which is uncer- 
tain, and which feeds upon the larva of Aleyrodes Prole- 
tella, whose body is margined on each side by eight tri- 
angular fleshy mammular processes, terminating each in 
a bristle, which give it a remarkable aspect a . The cu- 
rious scent-organs with which the larva of Chrysomela 
Populi is fringed have been before fully described ; and 
therefore I shall only mention them here b . 

In the larvae of the lace-winged flies (Hemerobius), and 
ant-lions (Myrmeleon\ the anus is furnished with a small 
fleshy retractile cylinder, from which proceeds the silken 
thread that forms the cocoon inclosing the pupa c . Pro- 
vidence has many different ways of performing the same 
operation. From the structure of the oral organs of 
these animals, the silk could not conveniently be fur- 
nished by the mouth ; the Allwise Creator has therefore 
instructed and fitted them to render it by a spinneret at 
the other extremity of the body. 

The respiratory anal appendages of many Dipterous 
larva? will be fully described in a subsequent Letter : I 
shall therefore now only further observe upon this subject, 
that although there is seldom any alteration in the form of 
these appendages &c. in the same species, the caterpil- 
lars of two moths (Centra Vinula and Attacus Tau)> how- 
ever, are exceptions. The former, when young, has two 
hairy projecting ear-like protuberances, which it entirely 
loses, as I have myself observed, before it assumes the 
pupa; and the latter, in like manner, after its third 

11 Reaum. ii. t. xxv.f. 20. 

b See above, Vol. II. p. 245 — . 

c Reaum. iii. 384. vi. 366. t. xxxii./, 7, 8. 



156 STATES OF INSECTS. 

change of skin, is deprived of its bent thorn-like points 
which attend it when young a . It is remarkable that 
these last larvae, when just excluded from the egg, are 
also entirely destitute of these appendages; they soon, 
however, appear, from slight elevations which mark their 
situation, and rapidly acquire their usual form b . Changes 
of a similar kind, hitherto unobserved, may probably 
take place in other species. 

iii. Figure. I am next to consider the general figure or 
shape of larvae. All of them, with but few exceptions c , 
agree in having a body more or less constricted at inter- 
vals into a series of rings or segments ,- usually in num- 
ber, twelve ; often nearly equal in length, but sometimes 
in this respect very dissimilar d . The general outline or 
shape of the body is extremely various : most frequently 
it approaches to cylindrical, as in most of the caterpillars 
of Lepidoptera, and of the Hymenopterous tribe of saw- 
flies [Tenthredo L.). The next most common figure is 
that more or less oblong or oval one, sometimes ap- 
proaching to conical, found in many of the larvae usually 
called grubs; such as those of the weevil {Curculio L.) and 

a Ro's. iii. t. Ixviii./. 1. Meinecken Naturf. vi. 120. 

b Ibid. xiii. 175. 

c In the larva of Tenthredo Cerasi L., and some others, no traces 
of segments are to be seen ; and in many coleopterous and dipterous 
ones the folds of the skin prevent the segments from being distinctly 
perceptible. 

d Reaum. ii. 361 . In the larva of a small common moth often met 
with in houses {Aglossa pinguinalis), every segment is divided into two 
parts, and underneath has two deep folds, by means of which these two 
parts can separate to a certain point, or approach again, according to 
circumstances. Thus Providence has enabled them to prevent their 
spiracles from being stopped by the greasy substances on which they 
often feed. N. Diet. d'Hist. Nat. i. 208. 



STATES OF INSECTS. 157 

of the Capricorn (Cerambyx L.), and other coleopterous 
tribes ; of bees, and all Hymenopterous insects but the 
saw-flies; and also of a large number of flies (Diptera). 
In some the figure approaches to fusiform, as in most of 
the moths of the Fabrician genus Lithosia. In others, 
as in those of the water-beetles (Dytiscus, &c), it ap- 
proaches to an obovate shape, being widest towards the 
head, and terminating in a point at the anus. In others, 
again, it isiinear ; an example of which is that ofStaphy- 
linus. Some are convex, and others gibbous, above, and 
flat underneath ; as those of Silpha, Chrysomela and many 
other beetles. Others are flat, both above and below, 
and depressed like a leaf; a remarkable instance of which 
has been before noticed a . Some are very long, as those 
of most Lepidoptera ) others very short, as that of the 
ant-lion (Myrmeleo?i). Many other peculiarities of form 
in individuals might be instanced ; but a dry enumera- 
tion of these would be of no great use to you. They can 
only be advantageously learned by the study of good 
figures, and by watching the actual metamorphosis of the 
singularly-formed larva? that you meet with. 

Instead, therefore, of any further specification of indi- 
vidual forms, I shall now endeavour to give you, as far 
as my own knowledge of them and the information I can 
collect from other sources will enable me, a larger and 
more general view of the kinds of larvae ; for analytical 
inquiries lose half their value and importance unless we 
proceed to apply them synthetically, by forming, if pos- 
sible, into groups the objects with which we are indivi- 
dually acquainted. 

Partial attempts at a synthetical arrangement with re- 
a See above, p. 110. 



158 STATES OF INSECTS. 

gard to the larvae of Lepidoptera and the saw-flies ( Ten- 
thredo L.) have been made both by Reaumur and De 
Geer. M. Latreille also has recently given a Tableau 
methodique et general of articulated animals furnished 
with jointed legs, considered in their first state a . The 
former of these is chiefly founded upon the number of 
the prolegs, and the latter upon the metamorphosis, pro- 
legs, habits, head, and parts of the mouth, without any 
other notice of the configuration. Mr. Wm. MacLeay, 
who, though young in years, is old in science and critical 
acumen, has started a perfectly new hypothesis upon this 
subject. In the progress of his inquiries into the natural 
arrangement of animals, particularly of insects in the 
Linnean sense, he has been the first to observe, that the 
relation which organized objects bear to each other is of 
two kinds ; one of real affinity, and the other only of ana- 
logy, or resemblance. This important distinction, upon 
which I shall enlarge in a future Letter, when I come to 
treat of Systems of Entomology, he has applied, in a way 
quite original, to larvae in general, but more particularly 
to those of the Coleoptera order. For the basis of his 
system he assumes a relation of analogy between the 
larva of Insects that in the progress of their metamor- 
phosis assume wings, and those that do not, which form 
his class Ametabola, so that the prototypes of the former 
shall be found amongst the latter 5 . But though Mr. 
MacLeay appears to consider the analogy between these 
two as primary, he extends it in a secondary sense to the 
Crustacea, at least in several instances c . Upon this oc- 

a 2T. Diet. d'Hist. Nat. xvii. 329. 

b Hor. Entoviolog. 285. 397—. 422. 462—. &c. 

c Ibid, 399—401. 



STATES OF INSECTS. 159 

casion he very judiciously remarks, that " in terming 
larvae Chilognathiformes or Chilopodiformes, it is not 
meant that they are Scolopendrce or lull, or even near to 
them in affinity ; but only that they are so constructed 
that certain analogical circumstances attending them 
strongly remind us of these Ametabola*." This remark 
you will bear in mind while I am treating of this subject. 
It should seem from another part of the same paragraph, 
that the comparison which our learned Physiologist re- 
commends, is between the young of the Ametabola and 
the larvae of the corresponding groups of Coleoptera. 
This must be understood to refer chiefly to the young of 
the Chilopoda and Chilognatha, since they approach 
nearer to them in that state, having then only six legs ; 
but the rest of the Ametabola should certainly be brought 
to this comparison in their adult state : and even the two 
former orders in that state more strongly resemble nume- 
rous coleopterous larvae, than when they are young and 
much shorter. I before called your attention to the re- 
markable circumstance that contrasts very many larvae 
of Hexapod insects that become winged in their perfect 
state with adult Myriapoda .• namely, that in one the pro- 
gress to this state is by losing their prolegs and shorten- 
ing their body ; while in the other, the reverse of this 
takes place, numerous prolegs and additional segments 
being gained before they arrive at maturity 5 . As the 
multiplication of organs is a sign of imperfection, it may 
be affirmed of the former of these tribes, that their pro- 
gress is towards greater perfection; while that of the 
other may be called a degradation. As larvae may be 
regarded as a stepping-stone by which approach is made 

* Hor. Entomolog. 423. b See above, p. 23. 



IgO STATES OF INSECTS. 

from the apterous to the winged tribes of Insects, it seems 
most consistent with general analogy that each should 
connect with the other in that state in which the resem- 
blance is greatest. Now the Myriapoda resemble larva?, 
as we have just seen, most when in their adult state; 
therefore the comparison should be between larvae and 
adult Myriapoda. 

Mr. MacLeay divides coleopterous larvse into five tribes 
thus characterized : — 

1 . A carnivorous hexapod larva, with an elongate linear 
Jlattened body, having a large head armed with two sharp 
falciform mandibles, and furnished with six granular eyes 

on each side. This kind he denominates Chilopodiform, 
as having for its type in the Ametabola, Scolopendra L. 
The examples he gives are Carabus and Dytiscus. 

2. A herbivorous hexapod larva, with a long and al- 
most cylindrical body, so fashioned that the posterior ex- 
tremity being curved under the breast, the animal when at 
rest necessarily lies like an Iulus on its side. This tribe 
he denominates Chilognathiform, from Iulus L. His ex- 
amples are, the larvae of Petalocerous insects, as Scara- 
ba?us L., Lucanus L. &c. 

3. An apod larva, having scarcely the rudiments of an- 
tenna, but which is furnished instead of feet with fat fleshy 
tubercles; which, when continued along the bach and belly, 
give the animal a facility of moving in whatever way it 
may be placed. These he denominates Vermiform, from 
certain of the Vermes intestina and Mollusca of Linne 
which he has associated with life Annulosa a . His exam- 
ples are, Curcidio L. and Cerambyx L. 

4. A hexapod and distinctly antenniferous larva, with a 

a The Intestinaiu cavitaires of Cuvier, and the E2?izoaria of La- 
marck. See Hor. Entomolog, 286 — . 



STATES OF INSECTS. 161 

subovate rather conical body, of 'which the second segment 
is longer and of a different form from the others, so as to 
give the appearance of a thorax. His denomination for 
these is Anopluriform, from Pediculus L., forming Dr. 
Leach's AnoplUra. His examples are, Coccinella and 
Chrijsomela L. 

5. A hexapod antenniferous larva of an oblong form, 
having like the former vestiges of a thorax, besides t*wo or 
more articulated or inarticidatcd setaceous or corneous ap- 
pendages to the last segment of the abdomen. This tribe 
he calls Thysanuriform, from Lepisma and Podura L., 
forming M. Latreille's order Thysanura. His example 
is Meloe with a note of interrogation a . 

The system here stated, of naming and characterizing 
larvae from the resemblance and analogy, in many cases 
very striking, that they bear to the apterous tribes, is a 
very happy and original one, and does its author great 
credit; yet I think in some instances, as I shall soon 
have occasion to point out to you, the application of it is 
not so happy as the first idea. But this is always the 
case when a new law of nature is discovered ; the proper 
application of it is gradually developed, and it does not 
at all detract from the merit of the first discoverer, that 
all the bearings of such law do not strike him as it were 
intuitively. 

a Hoi: Entomolog. 422. comp. 463. Mr. MacLeay's idea of the 
larva of Meloe is taken from the animal which Frisch, Goedart, and 
De Geer imagined to be such; but upon this opinion there rest great 
doubts. (See Kirby Mon. Aj>. Angl. ii. 168, and Latreille N. Diet. 
(FHist. Nat. xx. 109.) At p. 464 he gives also Mordella and many 
Heteromera as having Thysanuriform larvae. He thinks, that proba- 
bly that of Clerus is of the same description ; to which he suspects 
that many of Latreille's Malacoderma likewise belong. 

VOL. III. M 



162 



STATES OF INSECTS. 



Having, however, got the vantage-ground afforded by 
this discovery of my friend, let us see if by standing upon 
it we cannot get a tolerable generalization of the larvae 
of all orders of insects that undergo a metamorphosis. 
But first I must observe, that as in the perfect animals, 
so in their larvae, the different groups are connected by 
certain transition species, exhibiting characters common 
to two or more of them ; and likewise that in many cases, 
which you will see as we proceed, the analogy is as strong 
or stronger between them and the Crustacea (and in a 
few instances AracJniida, and even Mollusca) than the 
Ametabola. My denominations, therefore, will be taken 
from those tribes where the analogy appears to me the 
most striking, and not from the Ametabola alone. 

I shall begin by drawing up for you a list of the Pri- 
mary forms that I seem to have observed, and their cha- 
racters ; and then going through the orders, shall give 
you the examples of each, with such observations upon 
them as the case may require. 



Primary Forms of Larvce. 



APTERA. 

Anopluriform. 
Thysanuriform. 
Chilopodiform. 
Chilognathiform. 



ARACHNIDA. 

Araneidiform. 



CRUSTACEA. 

isopodiform. 

Onisciform. 

Idoteiform. 

Amphipodiform. 

Stomapodiform. 

Decapodiform. 

Branchiopodiform. 



MOLLUSCA. 

LlMACIFORM. 



ANNELIDA. 

Vermiform. 



Characters. 
1. Anopluriform. Carnivorous; hexapod; antenniferous: 
with a shortish oblong depressed body, and distinct 



STATES OF JNSECTS. 163 

thoracic shield. Example: Psoais, Coccinella> most 
Hemiptera a . 

2. Thysanuriform. Polyphagous; hexapod; antenniferous : 

body with segments of trunk distinctly marked; anus 
often furnished with setae or mucro. Ex. Meloe b ? 
Thrips, Aphis. 

3. Chilopodiform. Carnivorous; subhexapod; antennife- 

rous : body depressed, elongate, linear, with falcate 
acute mandibles, a distinct thoracic shield, and an 
anal proleg. Ex. Cicindela c ? Carabus L. 

4. Chilognathiform. Herbivorous: body subcylindrical, 

elongate, linear; no thoracic shield; often many pro- 
legs, sometimes a retractile one, and sometimes none. 
— Ex. Elate?; Petalocera, most Lepidoptem^ Ten- 
tliredo L. d 

5. Vermiform. Polyphagous ; apod or hexapod : with 

very short legs; antennae nearly obsolete; body 
fleshy, plicate, with sides often plicato-papillose ; 



a Plate XVIII. Fig. 1. as to the thoracic shield. 

b May 27, 1822. This day, T. Allen, Esq. F.L.S. brought me in 
a phial a vast number of the little insect which Goedart, Frisch, and 
De Geer took for the larva of Meloe Froscarabceus, which he found 
on the leaves of Achillea Millefolium. These little animals were 
coursing each other with wonderful velocity over the sides of the 
phial. To assist them in their motions, they applied to the surface 
of the glass the end of their abdomen, using it, like many larva? of 
Coleoptera, as a seventh leg. This circumstance excited a suspicion 
in the minds of both Mr. MacLeay sen., then visiting me, and my- 
self, that after all they might be coleopterous larvae. One, amongst 
other circumstances, however, seemed to militate strongly against 
this opinion ; namely, that in this infinite number none appeared to 
differ in size. 

c Plate XVII. Fig. 13. 

•» Ibid. Fig. 12.; Plate XVIII. Fig. 4, 11, 13, &c. 
M 2 



164* STATES OF INSECTS. 

no distinct thoracic shield. Ex. Cvrculio L., Ce- 
rambyx L., Musca L., and many other Diptera a . 

6. Araneidiform. Carnivorous ; hexapod : body very 

short ; mandibles long, suctorious ; animal lying in 
wait for its prey in a pitfall it has prepared; motion 
retrogressive. Ex. Myrmeleon L. b Cicindela ? 

7. Isopodiform. Saprophagous ; hexapod; antenniferous, 

with longer antennae : body oblong ; thoracic shield 
distinct; anus styliferous or laminiferous. Ex. 
Blatta L. Silpha L. ? 

8. Onisciform. Herbivorous ; polypod ; antenniferous : 

body short, oblong, depressed, margined. Ex. Ery- 
cina, Lyccena, in the Lepidoptera, and some species 
of Tenthredo L. c 

9. Idoteiform. Subcortical; hexapod; antennae obso- 

lete : body much depressed, with the last segment 
elongate, terminating in three or more mucros. Ex. 
Larva from Brazil. Perfect insect at present un- 
known. 
I have placed this larva, which was described above d , 
amongst crustaceous forms, because of the remarkable 
resemblance which the last segment of the body bears to 
that of the Idoteidce ; but I do it with considerable hesi- 
tation, since in other respects its type seems to be in the 
Ametabola. In its want of antennae, very short legs, and 
ventral asperities, it resembles some of the Vermiform 
larvae ; in its small head, distinct thoracic shield, and ob- 
long shape, it approaches the Anopluriform : and in its 

a Plate XVIII. Fig. 3, 9. ■> Plate XIX. Fig. 8. 

c Ibid. Fig. 3. Reaum. v. 97. t. xii./. 17, 18.; De Geer ii. 1004. 
t. xxviii./. 12. 
« See above, p. 1 10, 114, 138, 142. 



STATES OF INSECTS. 165 

very depressed body, but not at all in other respects, 
the Chilopodiform. At any rate, it appears of a primary 
Type. 

10. Lcemodipodiform. Herbivorous; hexapod; antenni- 

ferous, with long antennae: body elongate, subcylin- 
drical ; second segment of the trunk the longest ; 
anterior pair of legs distant from the other two. Ex. 
Phasma. 

11. Amphipodiform. Herbivorous; hexapod; antenni- 
ferous, with long antennae: body shortish, com- 
pressed, saltatorious. Ex. Gryllus L. a 

12. Stomapodiform. Carnivorous or saprophagous ; hex- 

apod; antenniferous, with long antennae: body elon- 
gate, subdepressed, with raptorious hands, and ab- 
domen wider than the trunk ; in aquatic species fur- 
nished with lateral gills. Ex. Mantis, Ephemera ? 
Sialis ? 

13. Decapodiform. Carnivorous; hexapod; antenniferous: 

body elongate, narrow, convex, compressed, taper- 
ing towards the tail ; tail with natatorious laminae. 
Ex. Dytiscus L., Agrion F. b 

14-. Branchiopodiform. Carnivorous?; aquatic; apod; 
antenniferous: head distinct: body transparent, flex- 
ile, furnished with a respiratory tube just above the 
tail. Ex. Culex c . 

15. Limaciform. Herbivorous; apod, or with very short 
legs: body ovate or obovate, slimy. Ex. Apoda 
Haw., Tenthredo Cerasi L. 

' Plate XVIII. Fig. 7. b Plate XVIII. Fig. 5. 

c Plate XIX. Fig. 9. 



166 STATES OF INSECTS. 

The above are the principal forms that appear to me 
Primary (though some doubt may rest upon the ninth 
and tenth) ; and probably others will hereafter be disco- 
vered, since at present our knowledge of the larvae of 
most of the Orders is very limited. And now having given 
you this generalization of them, as far as they are known 
to me, I shall next, in a slight survey of those of the dif- 
ferent orders, lay before you what I have further to ob- 
serve upon this subject. 

Coleoptera. The Anopluriform coleopterous larvse, ac- 
cording to Mr. W. MacLeay's view of them, include 
both those of Coccinella L., Chrysomela L., and Cas~ 
sida L. ; but this appears to me to admit of further con- 
sideration. With regard to the two former — those of 
Coccinella are carnivorous, those of Chrysomela herbi- 
vorous ; the first is also usually more flat and depressed. 
As to the latter, Cassida a , it seems to me to belong to a 
peculiar type, distinguished not only by its radiated mar- 
gin, but by the remarkable deflected anal fork on which it 
carries its excrement. At present I know no analogous 
form amongst the apterous tribes ; I must therefore leave 
this without a denomination. Perhaps the larva of Hispa 
or Alurnns, when known, will throw light upon this sub- 
ject. The larva of Endomychns agrees with that of Coc- 
cinella. 

There are very few known larvae that approach to a true 
Thysanuriform type in this order: that most celebrated is 
the one supposed to belong to Meloe ; but the claim of this 
to be so considered, is, as we have seen, rather dubious. 
Should this point at last be satisfactorily ascertained, it 

1 Plate XVIII. Fig. % 



STATES OF INSECTS. 167 

will probably carry with it the whole tribe of vesicatory 
beetles. But even this animal in its general structure is 
anopluriform ; the only circumstance that gives it any ana- 
logy to the Thysanura being its anal setae. Mr. William 
MacLeay is inclined to regard some of the larvae of the 
Malacodermi Latr., but which of them he does not state, 
as probably belonging to the tribe in question a . Those of 
Lampyris and of Telephones, as described and figured by 
De Geer b , appear to me intermediate between the Ano- 
pluriform and Chilopodiform Types : they have no anal 
setiform or styliform appendages, their mandibular are 
falcate, and their habits seem carnivorous. 

Examples of Chilopodiform coleopterous larvae are 
more numerous. Of this description are those of Gy- 
rimis, Cicindela, Carabus, and Staphylinus. That of the 
first, indeed, appears to be the most perfectly Scolopen- 
driform of any yet known; yet the gills or respiratory 
laminae, a pair of which issues from each abdominal seg- 
ment, and two pair from the last c , prove that there is 
no slight analogy between it, and indeed many other 
aquatic larvae, and the Stomapoda amongst the Crustacea. 
A remarkable instance of analogy with the Decapoda of 
the same Class is presented by the larva of JDytisctis, &c. 
which Mr. MacLeay considers as Chilopodiform^ but 
which exhibits no other resemblance to Scolopendrce than 



* Hor. Entomolog. 465. b De Geer iv. 66. i. ii./. 5—8. 

c Ibid. t. xm.f. 16 — 19. A very singular larva, -which preys upon 
that of Aleyrodes proletella Latr., if Reaumur's figure be correct (ii. 
t. xxv. f. 18 — 20), is of a perfect Chilopodiform type, the abdomi- 
nal legs being represented by a tubercle crowned by a bristle: yet 
even this, which turns to a minute beetle (Ibid./. 21), has some ten- 
dency to the Anopluriform type. 



168 STATES OF INSECTS, 

in its predaceous habits and threatening aspect. Its 
convex, compressed, tapering body, terminating in setae 
or laminse, is certainly much more like that of a shrimp 
or a prawn ; to which the older Entomologists thought it 
was akin a , and after which they named it. As Mr. Mac- 
Leay's object was, to take all his forms from the Ameta- 
bola, perhaps these larvae will best fall in with his Chilo- 
podiform type ; though in the general form of their body 
they most represent a section (Lepisma L.) of the Thy- 
sannra. 

Chilognathiform forms are equally numerous in the 
Coleoptera with the preceding. The wire-worm, or larva 
of Elater Segetis, as to shape best represents the full- 
grown Iuliis b , and those of the Petalocera (Scarabccus L., 
Lucanus L.) the young one. 

The most abundant of all forms in this order, is, I 
think, the Vermiform, upon which I have nothing further 
to remark. 

With regard to Crustaceoiis forms in Coleoptera, be- 
sides the Decapodiforni just noticed, I possess two speci- 
mens of larvae of Silphida: which seem to exhibit a con- 
siderable analogy with the Isopodous Crustacea, one rather 



a " Squilla insectum a squilla puce parum diff'ert." Mouffet, 319. 

b A remarkable difference obtains between the larva of the wire- 
worm and that of Slater undulatus. In the former, the last segment 
is longer than the preceding one, terminating in a small acute mucro 
at the apex, with a deep cavity, perhaps a spiracle, on each side, at 
the base. In the latter, this segment is shorter than the preceding 
one, forming above a nearly circular plate ; the margin of which is a 
little elevated, and armed on each side with three teeth, and at the 
apex with a pair of furcate recurved horns, and without any basal 
spiracle. De Geer iv. 156. 1. v./. 25, I have a similar larva, but not 
the same species. 



STATES Or INSECTS. 169 

convex and the other flatter, so as to give the idea of an 
Armadillo and of an Oniscus. 

Strepsiptera. Larva Vermiform. 

Dermaptera. Larva Thysanuriform. Type Podura or 
Sminthurus. 

Orthoptera. Mr. MacLeay considers the larvse of this 
Order as primarily Thysanuriform a , though he allows 
the resemblance between them and Amphipoda to be par- 
ticularly striking 5 . For my own part, their prototypes ap- 
pear to me to be in the Crustacea, and their analogical re- 
lations to the Thysanura much more distant. I trust this 
will appear to you the reverse of dubious in a progress 
through the Crustaceous Orders. I begin with the Iso- 
poda. Take the larva of a Blatta, and place it between 
a Lepisma, or Machilis, and an Oniscus, or Porcellio ; 
you will find that in shape and width, and the form of its 
anal styles, it resembles the latter much more than it does 
the former, with which it possesses scarcely any character 
in common, except its multiarticulate antennae. It is re- 
markable, that amongst the Blattida we meet with spe- 
cies that represent both the Oniscidce and Armadillo or 
Glomeris c , the latter being more convex than the former. 
In their habits the Blattae certainly agree with Lepisma ; 
and Dumeril, who thought the latter and Podura sub- 
ject to a metamorphosis, imagined they were related d . 

The Spectres of Stoll {Phasma F.) are so strikingly 
analogous to another crustaceous tribe, the Lcemodipoda, 
particularly the genus Caprella, that Montagu gave one 
species the Trivial name of Phasma e . The jumping Am- 

a Hor. Entomolog. 397. " Hid. 399. c Ibid. 438. Note *. 

d Traite Element, ii. 35. n. 577. 

" Trans. Linn. Soc. vii. 6b". t. \i.f. 3. 



170 STATES OF INSECTS. 

j)hipodiform Crustacea are represented extremely well by 
Gryllus L., and the Stomapodiform, particularly Squilla 
Mantis, by Mantis. The resemblance in this last instance 
is so very striking, that it cannot escape the eye of the 
least intelligent observer. Orthopterous insects may per- 
haps one day be discovered analogous to the two other 
crustaceous orders, the Decapods and Branchiopods ; but 
at present I know of none of that description. 

Hemiptera. The larvae of this order, which in general 
resemble the perfect insect, except that they have no 
wings, seem most commonly to belong to the Anopluri- 
Jbrm type a ; but the Aphides, Chermes, and Thrips may, 
I think, be regarded as more analogous to the genera 
Podura and Sminthurus in the Thysanura b . I have some 
suspicion that the Nepidce, Naucoris, and the remipedes, 
Notonecta, Sigara, &c. may find their prototypes amongst 
the Crustacea ,■ but my confined knowledge of the latter 
does not enable me to point to any individual genera or 
tribes that they may be presumed to represent. 

Neuroptera. As the kinds of larvae of the different tribes 
composing this order, as it now stands, are very various, 
it is to be expected that the analogical forms they repre- 
sent are equally so. The Libellidina MacLeay (whose 
metamorphosis that gentleman has denominated sub- 
semicomplete, a term warranted by their losing in their 
perfect state the mask before described ) in their oral 
organs, particularly by their galeate maxilla and distinct 
ligula d , have some relation to the Orthoptera, the proto- 
types of whose larvae we have found amongst the Crus- 

3 Compare De Geer iii. t. xi./. 3. and t. xvii./. 14. &c. 

b Ibid. t. If. 4, 9. t. n.f. 15. t. \x.f. 4. c See above, p. 125—. 

rl Compare Plate VI. Fig. 6. with Fig. 12 c,d, d. 



STATES OF INSECTS. 171 

tacca : probably, therefore, those of the tribe in question 
lurk in that class ; a suspicion that receives strong con- 
firmation from the larva of Agrion a , which in its taper- 
ing body and anal natatorious laminae represents a shrimp. 
Thelarvae of that very peculiar and distinct tribe, theEphe- 
merina, appear to be intermediate between the Stomapo- 
diform and Thysanuriform types. Their natatory respira- 
tory abdominal laminae seem copied from the former, and 
their anal diverging setse from the latter b . The Myrme- 
leonina, as well in their general form as in their motions 
and habits, present a most singular analogy with the tribe 
of spiders, as does also in some respect that of Cicindela. 
With regard to Panorpa, which Mr. MacLeay remarks 
is related to Mijrmeleon , and is a most ferocious insect d , 
as its larva has not yet been discovered, nothing certain 
respecting its analogical form can be asserted; but should 
it, like the male fly, represent the scorpion, both orders 
of Arachnida will have their representatives in the class 
we are considering. The Corydali?ia, as far as the larva 
of Hemerobius instructs us, is Chilopodiform, but with a 
tendency to the Araneidiform Type. The Ametabola 
also furnish the prototype of the next tribe, the Termi- 
tina, which, as is evident both from Psocus and Termes, 
are perfectly Anopluriform. The Sialina, or Plicipennes 
of Latreille, excluding Trichoptera Kirby, appear to me 
to be intermediate between the Chilopodiform and Stoma- 
podiform Types, and not without some relation to the 
Thysanuriform. Their pediform, jointed, respiratory ab- 
dominal appendages, their head and falcate mandibles, 
seem copied from the first tribe. The same appendages 

a De Geer ii. t. xxi./. 4, 5. b Swamm. Bibl. Nat. t. xiii./l 1. 
€ Hot: Entomolog. 438. d See above, Vol. II. p. 256. 



172 STATES OF INSECTS. 

considered as organs of respiration, and their taper forks, 
are moulded upon the plan of the Stomapodiform Crus- 
tacea, and the long seta which terminates the abdomen is 
upon the Thysanuriform plan a . 

Trichoptera. The larvae of this order appear also to 
be constructed upon a double plan. The respiratory 
threads observable in both the upper and under sides of 
the abdomen connect it with the Stomapoda, and its cy- 
lindrical elongate body with Chilognathiform types in the 
Lepidoptera b . 

Lepidoptera. The great majority of larvae in this or- 
der are Chilognathiform, but there are exceptions to this 
remark. Those of the Geometrce recede from this type, 
both in their motions and the distance and number of 
their legs. In both these respects they represent the Lce- 
modipoda in the Crustacea c . Other caterpillars are Onis- 
ciform ,■ and a third sort seem to leave the Annulose type, 
and imitate that of the Mollusca, and one is figured by 
Madame Merian d which appears to tend even to the 
Chilopodiform type. 

Hymenoptera. In this order the larvae of the saw-flies, 
Tenthrcdo L., are in general Chilognathiform, though some 
are Onisciform, others Limaciform, and those of Lyda F. 
[Cephaleia Jur.) and Sir ex e have a Vermiform tendency, 

a De Geer ii. t. xxiii. /. 9 — 14. Comp. Reaum. iv. t. xv. 
/• 1, 2. 

b De Geer ii. t. xiv./. 7. &c. The caterpillar of P. G. Scratiotata 
L. like those of Phryganece, has these respiratory threads. Ibid. i. 
t. xxxvii./. 2 — 6. De Geer has described the larva of a Phryganea L. 
which is without any respiratory threads, ii. 569. t. xv./. 10. 

c Hor. Entomolog. 401. Montagu in Linn. Trans, vii. 67. 

d Ins. Surinam, t. xxviii. Compare Ibid. t. xix. right-hand figure. 

* Plate XVIII. Fig. 10. 



STATES OF INSECTS. 173 

and are a stepping-stone to those of the rest of the order, 
which are all Vermiform and apods. 

Diptera. The majority of this order may be set down 
as Vermiform, though it is not improbable that some of 
them bear an analogy to animals that appear far removed 
from the Annulosa. Thus, the larva of Stratyomis Cha- 
meleon seems to exhibit no small resemblance to some of 
the Polypi vaginati in the Acrita subkingdom of Mr. W. 
MacLeay a . That of Culex and some others is con- 
structed on a quite different type from the rest, and seems 
to possess some analogy to the Branchiopod Crustacea. 

Though some of these analogies are more striking than 
others, yet in almost all that I have stated there is that 
kind of resemblance that could not be the result of what is 
called mere chance; and Mr. MacLeay, by first pointing- 
out this plan of the All-wise Creator, and by laying down 
the doctrine of analogies in general, as distinguished from 
affinities in the animal kingdom, has furnished the be- 
liever with a new argument against those attacks of the 
infidel, that would render null those proofs of the wisdom 
and goodness of the Author of nature with which the ani- 
mal and vegetable creation furnish us ; by affirming most 
absurdly, and under the most stultifying blindness of 
mind, that the creatures were in a manner their own cre- 
ators, their wants under local circumstances stimulating 
them to efforts that in a long course of years produced 
all the different forms and organizations that are now to 
be found in our globe. The affinities and close connexion 
of beings with each other, so that the ascent from low to 
high is usually by the most gentle gradations, is the cir- 

a Swamm. Bibl. Nat. t. xxxix. Plate XIX. Fig. 13, 



174 STATES OF INSECTS. 

cumstance on which they build this strange and impious 
theory. But the fact, that certain animals of one tribe 
were created with a view to certain animals of another, 
so as to present a striking aspect of correspondence, pa- 
rallel almost with that of type and antitype, without any 
real affinity or approximation; — this triumphantly proves 
a Power above and without them, who has associated 
them not only in a complex chain of affinities, but has 
caused them to represent and figure each other, even 
when evidently far removed, so as to give a mutual cor- 
respondence and harmony to the whole, which could be 
produced only by a Being infinite in power and wisdom, 
who made all things after a general preconceived plan 
and system. 

iv. We are now to consider the clothing with which 
larvae are furnished. Many are quite naked, and smooth 
or rough only with granular elevations or tubercles or- 
derly arranged; but a very considerable number, espe- 
cially of the Lepidoptera order, are clothed with hair or 
bristles of different kinds, in greater or less abundance, 
and arranged in different modes ; and a proportion still 
smaller have their skin beset with spines or a mixture of 
spines and hairs. Lyonnet found that the hairs of the 
caterpillar of the great goat-moth ( Cossus ligniperda) were 
hollow, though not to the apex : probably this is the case 
with those of other larvae, as well as with their spines. 
In this instance they were set, he observes, in a corneous 
ring, or very short cylinder, elevated a little above the 
skin. The hair passes through this ring, and appears to 
be rooted in a soft integument, which clothes the skin 
within, and upon which the nerves form a reticular tissue. 



STATES OF INSECTS. 175 

some of which he thinks he has even seen enter the root 
of the hairs, which perhaps are organs of touch a . 

Of the pilose larvae, some, like most of those of the 
smaller moths (Geo?netra, Tortrix, Pyralis, &c), have 
merely a few scattered short hairs, scarcely perceptible ex- 
cept through a lens: others [Odenesis Rotatoria, Lasiocam- 
pa Rubi) are covered with down more or less thick : in 
others (Eriogaster lanestris, Lasiocampa Neustria) the 
hair is slenderer, and more like wool; the body of two spe- 
cies which I purchased from the collection of Mr. Fran- 
cillon is covered with woolly hairs, so long as to give 
them the appearance of a shock-dog; and Madam Merian 
has figured a similar one, which she could not bring to the 
perfect state b . The hairs of many Bombycidce, known 
commonly by the name of hairy caterpillars, as Arctia er- 
minea, &c. are stiffer, resembling bristles ; sometimes, as 
in Arctia chrysorhea, mixed with shorter ones. The 
hairs either spring immediately from the skin (Noctua 
Aceris, lepmina), or, as is more general, proceed only 
from certain tubercular elevations, usually subhemisphe- 
rical, but sometimes conical ; of which a number varying 
from four to twelve are found on each segment of diffe- 
rent species. They seem to issue from these tubercles, 
as little diverging streams from the rose of a watering-pot. 
In both cases, they form a coating usually so dense as 
to conceal the body, but sometimes more thinly set, and 
admittins; the skin to be seen more or less between them. 
In a caterpillar of the beautiful Arctia ocidaria, the hairs 
are set upon tubercles alternately nearer the anterior and 
posterior margin of each segment, so as to form a dense 

a Lyonnet 69 — . h Surinam, t. Ivii. right-hand figure. 



176 STATES OF INSECTS. 

band, the rest being naked ; and in the lovely green and 
black one of Satumia Pavo?iia, each tubercle bears but 
six hairs, diverging like a star, the central one being the 
longest and capitate, so that the chief part of the body 
appears naked. This diverging position of the hairs is 
most common in the thick-clothed larvae also, but many 
have them placed differently : thus, in those of Callimor- 
pka Caja and Arctia villica a they are all directed towards 
the tail, like the quills of a porcupine : in some others 
the anterior ones point towards the head : in that of 
Eriogaster Quercus half of the tuft of hairs of each tu- 
bercle is directed downwards, the other half upwards : 
in that of Arctia Salicis all the hairs point downwards, 
so that the belly is thickly covered, while the back is 
bare. Another variation is, that the hairs of half the 
tubercle are sometimes very long, while those of the 
other half are very short, and even of a different colour b . 
In the larva of Tussuck moths {JLaria pudibwida, fasce- 
lina, &c.) the hairs are collected into tufts of a singular 
appearance, those on the intermediate segments of the 
back being quite level at the top, so as to resemble so 
many brushes; while those on the first and last segments 
are longer, and composed of feathered hairs converging 
to a point at their extremity, like a common camel-hair- 
pencil c . This last mode of arrangement prevails also in 
the larva of Nociua Aceris ; but in this the pencils are 
shorter, exactly wedge-shaped, and distinguished by an- 
other particularity, that of springing directly from the 

a Sepp iv. t. ii./. 3. t. xvi./. 2, 3. 
b JST. Diet. d'Hist. Nat. vi. 254. 

Plate XIX. Fig. 6. One of these larvae was taken at Mel- 
ville Island. See Parry's Voyage, Appendix No. x. 37. 



STATES OF INSECTS. 177 

skin, and not from a tubercle. This is also the case with 
the large caterpillars of Odenesis Rotatoria, which has a 
double row of short bundles of black hairs on the back, 
intermixed with larger ones : at each end of the body is 
a pencil of converging hairs, and the sides are spotted 
Avith bundles of white ones, which with longer tawny 
ones are bent downwards, so as to cover the sides of the 
creature a . Some have the anterior aigrettes disposed like 
the arms of a cross, of which the body of the caterpillar 
is the stem b . But not only is there considerable variety 
in the general arrangement of the hairs that clothe our 
little larvae, the hairs themselves differ much in their kind 
and structure, of which I will now, before I proceed to 
consider spines, give you some account. Several of them 
are feathered like the plumes of a bird : this is the case 
with those of Morpho Idomeneus, on each segment of the 
body of which are three blue tubercles, like so many little 
tui quois beads, from each of which proceeds a long black 
plume c . Other hairs terminate in a club ; those of the 
larva of Noctua Alni, a specimen of which I possess taken 
in England, are flat and incrassated at the apex, some- 
thing like the antennae of some Sphingidce. Mad. Merian 
has figured the caterpillar of another moth which feeds 
upon the Papaw-tree {Carica Papaya) with similar hairs d . 
But the most remarkable larva for the shape of its hairs 
is that of Anthrenus Musceorum, the little pest of our ca- 

a Sepp. iv. t. viii. /. 4. Some species have three, others four, 
and others even five of these brushes. 2V. Diet. d'Hist. Nat. vi 
255. 

b Ibid. Merian Eruc. xxxiv. upper left hand figure. 

Merian Ins. Surinam, t. Ix. 

d Ibid. t. xl. 
VOL. III. N 



178 STATES OF INSECTS, 

binets, which I noticed in a former letter a . All the hairs 
of its body are rough with minute points ; but those of 
six diverging long tufts or aigrettes, laid obliquely on 
the anal extremity of the body, which the animal when 
alarmed erects as a porcupine does its quills, are of a 
most singular structure : every hair is composed of a se- 
ries of little conical pieces, placed end to end, the point 
of which is directed towards the origin of each hair, which 
is terminated at the other extremity by a long and large 
conical mass, resembling somewhat the head of a pike b . 
Besides the one lately mentioned, other caterpillars 
are rendered striking by the brilliant colour of the tuber- 
cles from which their hairs emerge, A remarkable in- 
stance of this is the thick large caterpillar of a Bombyx, 
which feeds upon the Psidium pyriferum^ or white Guava, 
figured by Madame Merian. This caterpillar, which is 
white, with transverse black stripes, and which has two 
singular long converging curved bunches of hairs near 
the tail, is splendidly adorned on each side with fifty red 
tubercles, shining like coral, from which proceed six or 
seven long; diverging hairs. Leeuwenhoeck took these 
tubercles for eyes c . Another figured by the same lady, 
who mistakes it, with her usual inaccuracy, for the larva 
of a Lygceus F., and which seems by her description to 
be between the onisciform and limaciform types, has the 
apparently fleshy mamillae that project from its sides and 
back crowned with little hairy red globes, which give the 
animal a most singular and unique appearance d . Hav- 
ing thus described some of the principal modes in which 

a See above, Vol. I. p. 238. 

h De Geer iv. 207. t. viii./. 4—8. 

f Ins. Stir, t. xix, right hand caterpillar, d Ibid. xli. 



STATES OF INSECTS. 179 

the All-wise Creator has decked and defended these 
creatures with hairs, I shall next give you a short ac- 
count of the spines with which he has armed others. 
The spinous larvae are principally lepidopterous, and more 
particularly conspicuous in some tribes of the genus Pa- 
pilio L., though some saw-flies and Diptera are also di- 
stinguished by them. Vanessa Io % Atalanta and Urtica, 
Argynnis Paphia, Urania Leilus, and many other But- 
terflies, &c. are clothed with long sharp points, which 
claim the denomination of spines, rather than that of 
hairs or bristles ; being horny and hard, and so stiff at 
the point as readily to pierce the skin. Those of the last- 
mentioned species, Madame Merian says, are as stiff as 
iron-wire b . They are sometimes entirely simple, and 
look like spikes rather than spines, as in the caterpillar 
of Nymphalis Amphinome and Morpko Menelaus c ; but 
ordinarily they are beset with hairs, or more commonly 
with shorter spines, which often give them the appearance 
of plumes, as in Urania Leilus just mentioned: sometimes 
these lateral spines are so long as to have the appear- 
ance of a branch of a tree; this is strikingly the case with 
a small caterpillar which Captain Hancock brought from 
Brazil ; its body is so thickly planted with spines of this 
description, that it absolutely wears the appearance of 
a forest or thicket in miniature. A singular circum- 
stance attends the spines of this species : in many cases 
a smaller and very slender hair-like spine issues from 
them, resembling a sting ; and this accounts for an ob- 
servation of Abbott's, that many American caterpillars 
sting like a nettle, raising little white blisters on the skin 

* Plate XVIII. Fig. 13. 

b Int. Sttr. t. xxix. ' Ibid. t. vii. Hit. 

N 2 



180 STATES OF INSECTS. 

when accidentally or slightly touched a . Lewin has de- 
scribed the caterpillar of a moth found in New Holland, 
which he names Bombyx vnlnerans, that, like these Ame- 
ricans, has also the power of wounding, but in a different 
way. It darts out, he says, when alarmed by the ap- 
proach of any thing, from as many knobs or protube- 
rances in its back eight bunches of little stings, with 
which it inflicts a very painful and venomous wound b . 
The caterpillar of Papilio Protesilans F., if Madame Me- 
rian's account and figure of it are correct, has its body 
armed with hairy spines, the extreme point' of which is 
surmounted by a star-shaped appendage c . Those of a 
few saw-flies ( Tenthredo Pruni L.), and another figured 
by Reaumur d , are covered with a little forest of spines 
without lateral branches, but divided into a fork at the 
apex. Some spines are merely rough, with very short 
points, as those round the head, which give so terrific an 
appearance to the caterpillar of the Bombyx regalis> of 
some proceedings of which I gave you an account in one 
of my former letters e . 

I must now say something upon the arrangement of 
these spines. Though in a few instances so thickly set 
as entirely to conceal the body of the animal, as in the 
case of the Brazil one lately mentioned, yet generally 
speaking, even when they are most numerous, they per- 
mit the skin to be distinctly seen. Their arrangement 
is various, though always orderly : in the majority they 

a Smith's Abbotts Ins. of Georg. Pref. vi. 

b Prodromus Entomology. 

c Ins. Sur. t. xliii. The figure represents only the two spines near 
the head as thus circumstanced. 

d Reaum. v. i. xii./. 8, 14. Plate XVIII. Fig. 11. 

e See above, Vol. II. p. 238. This, with B. imperatoria, &c. in the 
modern system, should form a genus. 



STATES OF INSECTS, 181 

are planted singly, but in some caterpillars in bundles. 
In that of Satumia Io, on each segment there are six bun- 
dies of longish, quill-shaped, sharp, slender, diverging 
spines, which also appear to sheath aculei. Madame 
Merian has figured this larva, or one very near it, as the 
grub of a Euglossa a , with which, though she affirms she 
traced it to the fly, it can have no connection. With re- 
gard to number, some larvae have only four spines on 
each segment; others five, others again six, and others 
seven, or even eight : they are planted on the sides and 
back only, never on the belly. They are often more nu- 
merous on the intermediate than on the anterior and 
posterior segments; but sometimes the reverse of this 
takes place ; in that of Attacus Erythrince only the head 
and tail are armed with spines, the rest of the body being 
without any b ; and in that of Morpho Teucer there is 
only a single spine on the four intermediate segments c . 
They are usually all nearly of equal length ; but in some 
cases those of the head and tail are much longer than 
the rest, and remarkably so in the caterpillar of Urania 
Leilus, also beautifully plumose, and gracefully waved d . 
Those in the second and third segments are much longer 
than any of the rest in that of Bombyx regalis ,- which 
circumstance gives it the terrific appearance lately al- 
luded to. In the family to which Argynnis Paphia be- 
longs, the larva is adorned with two on the back of the 
first segment twice as long as the rest, and resembling 
at first sight two antennas. 

The spines, as well as the hairs of the new skin, are 
concealed under the old one, and not incased in its spines ; 

a Ins. Sur. t. xlviii. right hand figure, b Ibid. t. xi. 

c Ibid. t. xxiii. d Hid t, xxix. 



182 STATES OF INSECTS. 

but Bonnet ascertained, that if cut off very closely, the 
larva sometimes died in consequence, whilst no such re • 
suit followed a similar operation on hairy larvae. We 
learn from Reaumur a , that some spinous larvae of saw- 
flies ( Tenthredo L.) lose their spines at the last change of 
their skin; and from Madame Merian, that that of Atta- 
cus Erythrince before mentioned loses also at the same 
period the six tremendous black spikes that arm its black 
and yellow larvae. The grubs of ants that are destined 
to pass the winter in the larva state are hairy, but are not 
so in summer b . The spines found in the grubs of some 
gad-flies {(Estrus L.) are of a different kind from those 
above described, being very minute triangular flat plates, 
arranged in different and contrary directions c , and serv- 
ing the insect merely to change its place and fix itself d . 

Two other kinds of clothing, if so they may be called, 
neither coming under the description of hairs nor spines, 
are found in some other larvae, not only amongst the Le- 
pidoptera, but also in some of the other orders. Nym- 
phalis Populi and others of the same family have larvae 
furnished on the back of each segment with cylindrico- 
conical processes of a fleshy substance, obtuse at the apex 
and surrounded with capitate hairs. In that of N. Sy- 
hilla, which has on each segment two fleshy protube- 
rances, they are bifurcate or trifurcate, and also encir- 
cled at the base with a hairy tuft e . Others, as those of 
Melit(jea Artemis, Cynthia, &c. have each segment beset 
on the back with from seven to nine fleshy, pubescent, 
wedge-shaped protuberances ; two larger ones projecting 

a Reaum. v. 95. b Huber Mceurs des ftournm, 79. 

c See above, Vol, II. p. 276—. d Reaum. v. 72, /. ix, f. 2—4. 
e Rds. t.9\\. 



STATES OF INSECTS. 183 

over the head. Under this head, too, may be noticed, 
the glutinous secretion which clothes the grub of Cionus 
Scrophularice, a little weevil ; and of Tenthredo Cerasi L. 
a saw-fly, and that waxy or powdery substance which 
transpires through the skin of the larvae of several Aphi- 
des, Chermes, Cocci, Hylotoma ovata F., &c. The Aphis, 
whose extensive ravages of our apple-trees (A. lanata) 
were before described to you a , is covered and quite con- 
cealed by this kind of substance, so that the crevices in 
the bark which they inhabit look as if they were filled, 
not with animals, but with cotton. The insect, also, 
that forms those curious galls produced upon the spruce 
fir, and which imitate its cones [Chermes Abietis L., Aphis 
De Geer) secretes a similar substance. In these and 
other cases of the same kind, this matter seems to be, if 
I may so speak, wire-drawn through numerous pores in 
certain oval plates in the skin, more depressed than the 
rest of the back, arranged regularly upon the segments, 
and exhibiting minute tuberosities. When young, these 
animals have more of this secretion than when more ad- 
vanced : it then hangs from their anal extremity in 
locks b . 

But the insects most remarkable for a covering of this 
nature are those Coccidce of which Bosc has made a ge- 
nus under the name of Dorlhesia. De Geer is the first 
author that notices them, and has given a. description 
and figure of one species under the name of Coccus floc- 

3 See above, Vol. I. p. 29, 198—. 

b Tie Geer iii. 111. Comp. 121. It would be as well to adopt the 
French word flocon, instead of locks or floeksj which strictly mean 
very different things. 



184 STATES OF INSECTS, 

cosus a . It was discovered by Modeev upon some sere 
fir-leaves in a thick bed of moss. Panzer lias figured a 
second found upon Geranium sanguineum, which from 
the figure appears distinct from De Geer's, under the 
name of Coccus dubius b . Fabricius regards this as syno- 
nymous with the Dorthesia characias of Bosc, inhabiting 
Euphorbia characias in South Europe c . Olivier found 
a species upon the bramble d . I once took one, which 
appears to differ in some respects from the preceding spe- 
cies, upon Melampyfum cristatum, and our indefatigable 
friend Mr. Sheppard has sent me another, on what plant 
found I do not remember, which does not agree with any 
that I have mentioned. The body of the animals of this 
genus is covered by a number of cottony or waxy lamina? 
which partly cover each other, and are arranged usually 
in a triple series : in De Geer's figure the series appears 
quadruple, the lateral ones being placed obliquely. The 
anterior one in my specimen covered die head, and they 
are all canaliculate. Above the anus are four diverging 
ones : the whole are of the most dazzling whiteness. 
When these laminae are removed, the body appears di- 
vided into segments. 

With respect to those larva? which imitate slugs by the 
viscid covering that besmears them and issues from their 
pores, we learn from Professor Peck that this exudation 
takes place as soon as they are hatched ; that the animal 
retains its humidity although exposed to the fiercest heat 
of the sun, and that at the last moult the skin becomes 

* vii. 604. t.xliv.f. 20. b jr n . Germ. Init. xxxvi. 21. 

'■ fyst. Rhyng. 311. 29. J N. Diet. d'Hist. Nat. ix. 554. 



STATES OF INSECTS. 185 

quite clean, and free from all viscidity 3 It is probable 
that the other limaciform larvae are similarly circum- 
stanced. Madame Merian has figured an onisciform one, 
the legs of which, she says, are covered with a viscid skin: 
this produced a Noctua. Those of Papilio AvcMses also 
are slimy, and adhere to each other b . 

v. Amongst other qualities which attach to larvae, we 
must not omit to say something concerning their Colour. 
For though those which live in darkness, in the earth, 
in wood, in fruits, &c. are, with few exceptions c , of an 
uniform whitish colour, yet such as are exposed to the 
influence of the light are usually adorned with a vast va- 
riety of tints, sometimes the most vivid that can be ima- 
gined. That the white colour of the former may be at- 
tributed to the absence of light is proved by an experi- 
ment of M. Dorthes, who having forced some to live un- 
der glasses, exposed to the light, found that they gradu- 
ally became brown d . To attempt any classification of 
coloured larvae would be in vain, since they are tinged 
with almost every possible shade that can be conceived, 
of many of which it would be difficult to find examples 
elsewhere; and infinitely diversified as to the arrangement 
and figure of their multiform markings and spots. A few 
general remarks, therefore, are all that you will expect 
on this head. Many are of one uniform colour ; while a 
variety of tints, very different, and very vivid and distinct, 
ornament others. Sometimes they are distributed in 

a Natural History of the Slug-ivorm, 7. 

h Ins. Surinam, t. xv. xvii. 

c The larvae of Carabus L. form one., being generally black, 

d Annates de Chimie ii. 



1SG STATES OF INSECTS. 

longitudinal rays or bands, at others in transverse ones. 
Sometimes they are waved or spotted, regularly or irre- 
gularly ; at others they are sprinkled in dots, or minute 
streaks, in every possible way. Various larvae are of the 
colour of the plant on which they feed, whence they are 
with difficulty discovered by their enemies. Thus, a large 
proportion of Lepidoptera are green of different shades, 
sometimes beautifully contrasted with black bands ; a cir- 
cumstance which renders the caterpillars of two of our 
finest insects of this order as lovely as the fly : I mean 
that of Papilio Machaon and Satumia Pavonia. Very 
frequently the larvae of quite different species resemble 
each other so exactly, in colour as well as shape, as 
scarcely to be distinguishable : this sometimes takes 
place even where they belong to different genera, as in 
those of Bombyx versicolor a moth, and Smermthus Po- 
puli a hawk-moth. And it sometimes happens, very for- 
tunately for distinguishing allied species, that where the 
perfect insects very nearly resemble each other, the lar- 
vae are altogether dissimilar. Thus, the female of Pieris 
Rapce is so much like the same sex of Pieris Brassicce, 
that it might be taken for a variety of it, did not the 
green caterpillar of the one, and the spotted one of the 
other, evince the complete distinction of these butterflies. 
Noctua Lactuca, N. umbratica, and several other species 
of the same tribe, which includes N. Absinthii, Verbasci, 
Chamomillce, Abrotani, are so extremely alike, that the 
most practised eye can scarcely discover a shade of dif- 
ference between them, though their larvos in colour and 
markings are constantly distinct 3 . The markings of 

• Wien. Vera. 219. 



STATES OF INSECTS, 187 

species belonging to the same family are usually diffe- 
rent; but in some cases the latter maybe prejudged from 
the former. The larvae of many of the genus Sphinx L., 
for example, have their sides marked by oblique streaks 
running from the back in a direction towards the head ; 
and by this last circumstance they are distinguished from 
those of Bombyx xiersicolor, Attacus Tau, and others of 
the same tribe, which have also lateral oblique striae, but 
running from the back towards the tail a . The colours 
of individual larvae of the same species are usually alike, 
but in Sphinx Elpenor and some others they vary exceed- 
ingly. Many, like those of Lasiocampa Rnbi, Saiurnia 
minor, &c, are of one colour when first disclosed, and 
assume others quite different in riper age. Just previ- 
ously to changing their skin, the tints of most larvae be- 
come as dull and obscure, as they are fresh and vivid when 
the change has fully taken place ; and in some instances 
the new skin is quite differently marked from the old one. 
This is remarkably the case with the last skin of some of 
the larvae of the genus Tenthredo L., which is entirely 
different from all the preceding ones. As people when 
they advance far in years usually become more simple in 
their dress than when they were young, so the larvae in 
question change an agreeably variegated skin for one of 
a uniform and less brilliant colour b . Madame Merian 
has observed with respect to Attacus Erythrince, that its 
caterpillar is at first yellowish, with nine black striae 
on each side: when arrived at one third of its size, 
they become orange; the striae are obliterated, and in 
their place a round black spot appears on each of the 

a lYien. Verz. 4. b Reauin. v. 92. 



188 STATES OF INSECTS. 

eight intermediate segments a . Mr. Sheppard has re- 
marked to me, that the skin of that of Sphinx Ligustri, 
after being under ground four days, was changed from a 
vivid green to a dull red. Very rarely, however, it be- 
comes of a more brilliant hue just before entering the 
pupa state : thus, that of another hawk-moth (Smerinthus 
Tilice) changes to a bright violet ; and the yellow hairs 
of that of Laria pudibunda then become of a lovely rose 
colour. And here I may observe, that the hairs and 
spines also, of larva?, vary greatly in colour. They are to 
be met with brown, black, red, yellow, violet, white, &c. 
De Geer found, that in the larva of Chnbex nitens the 
two sides of the body were of a different colour, the 
left being of a deep green, whilst the right side and the 
rest of the body were paler b ; but as he saw only a single 
individual, this was probably an accidental circumstance. 
Though the caterpillars, as I lately said, of one of the 
most beautiful butterflies and moths that inhabit Britain 
contend with the perfect insect in loveliness, yet in gene- 
ral no judgement can be formed of the beauty of the fu- 
ture fly from the colour of the larva ; and the young Au- 
relian must not flatter himself always with the hope, be- 
cause the caterpillar excites admiration by its colours and 
their arrangement, that the butterfly or moth it is to pro- 
duce will do the same; nor ought he to despise and over- 
look a sombre or plain-coloured individual of the former, 
under the idea that it will produce one equally plain of 
the latter, for it often happens that the splendid cater- 
pillar gives a plain butterfly or moth, and vice versa. 
De Geer, however, gives us two instances of conformity 

;1 Ins, Surinam, t. xl. b ii, 1017 



STATES OF INSECTS. 189 

between the colours of the caterpillar and those of the 
future moth ; the one is that of the common currant- 
moth (Phalcena G. grossulariata L.), the caterpillar of 
which is white, ornamented with several black spots va- 
rying in size. At the two extremities it is yellowish, with 
a longitudinal ray of the same colour on each side, the 
head and legs being black. These colours are all to be 
found in the fly, the ground of its wings being white or- 
namented with many black spots of different sizes. Its 
upper wings are traversed by a yellowish band; and 
towards their base is a spot of the same colour. Its body 
is yellowish, with black spots ; but the head and legs are 
black a . The other is that of a green caterpillar, which 
gives a green moth, figured by Reaumur (Pyralis prasi- 
naria Fab.) b Sometimes, also, the sex of the future per- 
fect insect may be predicted from the colour it exhibits in 
its first state : thus, the brown caterpillars of Noctua Pro- 
nuba produce males, and the green ones females c . The 
sexes, also, of N. exoleta and Persicarice differ in that 
state. 

vi» To the full account of the Food of insects given in 
a former letter d , which had reference chiefly to their 
larva state, it is only necessary in this place to add a few 
particulars not there noticed. Many larvae when first 
excluded, as those of Pieris Cratcegi, &c. devour the 
shells of the eggs from which they have proceeded e ; and 



a De Geer i. 57. b Ibid. 58. Reaum. i. t. xxxix./. 13, 14. 

c De Geer ii. 400. d See above, Vol. I. Letters xii. xiii. 

e Bonnet (ii. 18) mentions, that the young larvae of a butterfly 
(Pieris Cratcegi), after devouring the exuviae of the eggs from which 
they were hatched, gnawed those which were not so : not, however, 



190 STATES OF INSECTS. 

others (Gerura V inula, Sphinx Euphorbia, Noctua Ver- 
basci), though their usual food is of a vegetable nature, 
eat with great apparent satisfaction the skins which they 
cast from time to time, not leaving even the horny legs. 
This strange repast seems even a stimulating dainty, 
which speedily restores them to vigour, after the painful 
operation by which they are supplied with it Under 
this head it will not be out of place to mention, that some 
larvae of insects, which feed only on the juices of animals, 
or the nectar and ambrosia of flowers, have no anal pas- 
sage, and of course no feces. This is said to be the case 
with the grubs of bees, wasps, the larvae oiMyrmeleon, &c. a 

vii. You will require no stimulus to induce you to at- 
tend to the subject I am next going to enter upon, — the 
Moulting, namely, of Larvae; or their changes of skin. 
This, indeed, is a subject so replete with interest, and 
which so fully displays the power, wisdom, and goodness 
of the Creator, affording at the same time such large oc- 
casion for nice investigation, that a pious and inquisitive 
mind like yours cannot but be taken with it. In the 
higher orders of animals, though the hairs of quadrupeds 
and the feathers of birds are in many cases annually 
renewed, the change, or scaling and increment of the 
skin, is gradual and imperceptible ; no simultaneous re- 

so as to destroy the included animal, but rather to facilitate its egress. 
Those also of Coccinella bipunctata which I lately bred from the e<Jg, 
as soon as hatched began to devour the unhatched ones around them, 
which they seemed to relish highly. I am inclined to believe, how- 
ever, that this unnatural procedure was to be attributed to the cir- 
cumstance of the female not having had it in her power to place her 
eggs in the midst of Aphides, their proper food. 
* N. Did. dtHist. Nat. xx. 359. 



STATES OF INSECTS. 19l 

jection of it, in which it is stripped off by the animal it- 
self like a worn shirt, being observable, till you descend in 
the scale to the Serpent tribe a , which at certain periods 
disengage themselves from their old integument, and start 
forth with that new and deadly beauty so finely described 
by the Mantuan bard : — 

" So from his den, the winter slept away, 

Shoots forth the burnished snake in open day; 

Who, fed with every poison of the plain, 

Sheds his old spoils and shines in youth again : 

Proud of his golden scales rolls tow'ring on, 

And darts his forky tongue h , and glitters in the sun." 

Pitt. 

In these the new skin, I imagine, is formed under the 
old from the rete mucosurti; but in insects, as I formerly 
stated c , since the time of Swammerdam it has generally 
been believed by entomologists, that the larva includes a 
series of cases or envelopes, one within the other, con- 
taining in the centre the germe of the future perfect insect, 
whose development and final exclusion take place only 
when these cases have been successively cast off. This 
hypothesis, as was explained to you on a former occasion d , 
has been controverted by a late writer, Dr. Herold ; who 
affirms that the skins of caterpillars are also successively 
produced out of the rete mucosum. I have however, I 
hope, satisfied you that the old system is most consonant 

a In the human species, after certain fevers a simultaneous and 
total moult, if the term may be so applied, takes place. I experi- 
enced this myself in my boyhood; when convalescent from Scarlatina, 
the skin of my whole body, or nearly so, peeled off. 

b The translator, more ignorant of natural history than his author, 
has turned the " Unguis micat ore trisulcis " of Virgil, into " darts hi? 
forky sting." 

c Vol. I. p. 70. d See above, p. 52'—. 



192 STATES OF INSECTS. 

to nature and probability : but as we are now to enter 
at large upon the Moults of insects, it will not be without 
use if I add a few additional reasons which seem to me 
still further to prove the correctness of Swammerdam's 
system, as far as it relates to that subject. With regard 
to the mere formation of the skin from the rele mucosum, 
were this the whole question few would hesitate to adopt 
the sentiments of M. Herold ; but when we come to con- 
sider further — that the number of moults of individuals 
of the same species is always the same, and that it varies 
in different species, and takes place at certain periods, — 
we begin to suspect that something more than the mere 
formation of a new skin upon an old one being cast is to 
be accounted for ; and that the law which prescribes its 
own definite number of skins to each species, must begin 
to act in the primordial formation of the larva. Again, 
the hairs observable in the higher animals do not take 
their origin from the epidermis solely, but are planted 
below it in the rete mucosum, or deeper a ; so that the 
change of skin does not affect them ; but in the larvas of 
insects they are a continuation of that integument, since, 
when the moult takes place, they always remain on the 
rejected skin b : this is the case, also, even with spines. 
If you shave a caterpillar ready to change its skin, either 
partially or generally, you will find that the parts in the 
new skin that correspond with those that are denuded, 
are equally hairy with those that were not c ; and if 
you pay attention to the new-clad animal, you will find 
f irther, that the hairs never grow after a moult. From 

a Cuvier Anat. Comp. ii. 596. N. Diet. d'Hist. Nat. xxvi. 165. 
b Cuvier Ibid. 624. <= Reaum. i. 183. 



STATES OF INSECTS. 193 

hence it follows, that the hairs have their place and take 
their whole growth between the new skin and the old a . 
Whether the spines, simple or compound, lately described 
to you, that arm some larvae are similarly circumstanced, 
seems not as yet to have been ascertained ; but as the 
spinous ones of certain Tenthredines L. and Lepidoptera 
at their last moult have no spines, the presumption is, 
that, whether incased or not, they are mere appendages 
of the skin on which they appear. A new set of hairs, 
therefore, and probably of spines in spinous larvae, ac- 
companying each skin, and these varying very much in 
size, composition, &c. though a new membrane may be 
admitted to be formed from an action in the rete mucosum 
without a pre-existent germe of it, it seems not easy to 
conceive how these hairs and spines can spring up and 
grow there, each according to a certain law, without ex- 
isting previously as a kind of carculum or punctum saliens; 
and that the germes of the tubercles, in which the hairs 
are so generally planted, according to a certain arrange- 
ment and in a given number, should also pre-exist, seems 
most consonant to reason. These and the several skins may 
all co-exist in their primordial germes, and remain be- 
yond the discovery of our highest powers of assisted vi- 
sion, till a certain period when they may first enter the 
range of the microscope-aided eye. It does not therefore 
follow, because these primordza semina rerum are not 
discoverable, that therefore they may not exist. Our 
faculties and organs are too limited and of too little power 
to enable us to see the essences of being:. 

Upon the supposition that the hypothesis of Swam- 

a N. Diet. d'Hist, Nat. vi. 290. 
VOL. Ill, O 



194 STATES OF INSECTS. 

merdam is the true one, we may imagine that the enve- 
lope that lies within all the rest is that which covers the 
insect in its pupa state. Above this are placed several 
others, which successively become external integuments. 
These changes or casting of the skin in larvae, analogous, 
as before observed, to that of serpents, are familiar to 
every breeder of silk-worms, in which four such changes 
occur : the first at the end of about twelve days from its 
birth, and the three next each at the end of half that time 
from the moulting which preceded it. With some ex- 
ceptions a , similar changes of the skin take place in all 
larvae, not however in the same number and at the same 
periods. Most indeed undergo this operation only three 
or four times ; but there are some that moult oftener, 
from five up to eight (Arctia villica), nine (Callimorpha 
Dominula), or even ten times; for so often, M. Cuvier 
informs us, the caterpillar of the tiger-moth (Callimorpha 
Caja) casts its exuviae. It has been observed that the 
caterpillars of the day- flying Lepidoptera (Papilio L.) 
usually change only three times, while those of the night- 
flying ones (Phalcena L.) change four b . The periods 
that intervene between each change depend upon the 
length of the insect's existence in the larva state. In 
those which live only a few weeks or months, they are 
from eight to twenty days ; while in those that live more 
than a year, as the cockchafer, &c. they are probably 
proportionably longer : though we know very little with 

a Those Diptera whose metamorphosis is coarctate (Vol. I. p. 67), 
bees, the female Cocci, &c. do not cast their skin in the larva state. 
Reaum. iv. 364. N. Diet. d'Hist. Nat. xx. 365. 

•> N. Diet. d'Hist Nat. vi. 289. xx. 372. Cuvier Anat. Comp. ii. 
548. M. Cuvier (Ibid. 547.) asserts, that most jPapiliones and Bom- 
byces moult seven times. 



STATES OF INSECTS, 195 

regard to the moult of any insects besides the Lepido- 
jptera. 

A day or two previously to each change of its skin, 
the larva ceases eating altogether; it becomes languid 
and feeble, its beautiful colours fade, and it seeks for a 
retreat in which it can undergo this important and some- 
times dangerous and even fatal operation in security. 
Here, either fixing itself by its legs to the surface on 
which it rests, or, as is the case with many caterpillars, 
by its prolegs, to a slight web spun for this purpose, it 
turns and twists its body in various directions, and alter- 
nately swells and contracts its different segments. The 
object of these motions and contortions seems to be, to 
separate the exterior skin, now become dry and rigid, 
from the new one just below it. After continuing these 
operations for some hours, resting at intervals without 
motion, as if exhausted by their violence, the critical mo- 
ment arrives : the skin splits in the back, in conse- 
quence of the still more violent swelling of the second or 
thifd segment : the opening thus made is speedily in- 
creased by a succession of swellings and contractions of 
the remaining segments : even the head itself often di- 
vides into three triangular pieces, and the inclosed larva 
by degrees withdraws itself wholly from its old skin. 
All larvae, however, do not force their way through this 
skin in precisely the same place. Thus, those of the haw- 
thorn butterfly (Pieris Crat<zgi\ according to Bonnet a , 
make their way out by forcing off what may be called their 
skull, or the horny part of their head, without splitting the 
skin, which remains entire; others have been observed 
to make their way out at the side and the belly. Reau- 

a CEuvr. ii. 71. 
O 2 



196 STATES OF INSECTS. 

mur noticed the larva of Zygcena Filipemhdtf, previously 
to its last moult, actually biting off and detaching several 
portions of its old skin; and before this, drops of a fluid 
resembling water were seen to exude from it a . 

The skin when cast is often so entire, that it might be 
mistaken for the larva itself; comprising not only the 
covering of the main trunk with the hairs which clothed 
it, but of the very skull, eyes, antennae, palpi, jaws, and 
legs ; which, if examined from within, are now found to 
be hollow, and to have incased, like so many sheaths, 
similar parts in the new skin. That the feet of the newly- 
coated larva were actually sheathed, as fingers in a glove, 
in the same parts of the exuviae, may be proved by a 
very simple experiment : if a leg of one just ready to 
cast its skin be cut off, the same limb will be found mu- 
tilated when that change has ensued. The anal horns, 
also, of the larvae of the hawk-moth (Sphinx L.) and other 
similar protuberances, are incased in each other in like 
manner ; but hairs are laid flat between the two skins, 
and contribute considerably towards their more easy se- 
paration. Thus, if you saved the skins cast by the larva 
of Callimorpha Caja, for instance, you would appear to 
have ten different specimens of caterpillars, furnished 
with every external necessary part, and differing only in 
size, and the colour perhaps of the hairs, and all repre- 
senting the same individual. 

But further changes than this take place. Swammer- 
dam says, speaking of the moult of the grub of Oryctes 
nasicornis, a beetle common in Holland, but not satis- 
factorily ascertained to inhabit Britain, " Nothing in all 
nature is in my opinion a more wonderful sight than the 

* Reaum. ii. 75.. 



STATES OF INSECTS. 197 

change of skin in these and other the like worms. This 
matter, therefore, deserves the greatest consideration, 
and is worthy to be called a specimen of nature's mira- 
cles ; for it is not the external skin only that these worms 
cast, like serpents, but the throat and a part of the sto- 
mach, and even the inward surface of the great gut, 
change their skin at the same time. But this is not the 
whole of these wonders ; for at the same time some hun- 
dreds of pulmonary pipes within the body of the worm 
cast also each its delicate and tender skin. These seve- 
ral skins are afterwards collected into eighteen thicker, 
and, as it were, compounded ropes, nine on each side of 
the body, which, when the skin is cast, slip gently and 
by degrees from within the body through the eighteen 
apertures or orifices of the pulmonary tubes before de- 
scribed, having their tops or ends directed upwards 
towards the head. Two other branches of the pulmo- 
nary pipes that are smaller, and have no points of respi- 
ration, cast a skin likewise." ..." If any one separates 
the cast little ropes or congeries of the pulmonary pipes 
with a fine needle, he will very distinctly see the branches 
and ramifications of these several pipes, and also their 
annular composition a ." — Bonnet makes a similar obser- 
vation with regard to caterpillars ; but he appears to have 
.observed it more particularly, at least the change of the 
intestines, previously to the metamorphosis of the insect, 
when he says with the excrements it casts the inner skin 
of the stomach and viscera 5 . Both these great men ap- 
pear to have recorded the result of their own actual ob- 
servations with regard to the proceedings of two very dif- 

a Bibl. Nat. E. Trans, i. 135. col. b. /.- xxvii./. 6. 
* (Eiivresy viii. 303. 



198 STATES OJF INSECTS. 

ferent kinds of insects; the one the grab of a beetle, and 
the other the caterpillars of Lepidoptera. The account of 
the former is given quite in detail, as that of a person who 
is describing what he has actually seen ■: yet by a later and 
very able physiologist, Dr. Herold, it is affirmed that the 
inner skin of the intestinal canal is never cast, that canal 
constantly retaining its two skins. He further affirms, that 
they are only the large trunks of the Tracheae that cast 
their skins, none being detached from their smaller rami- 
fications a . When men so eminent for their anatomical 
skill and nicety, and for their depth and acumen, dis- 
agree, the question must be regarded as undecided till 
further observations throw sufficient weight into one scale 
or the other. 

The larva which has undergone this painful process is 
at first extremely weak: all its parts are soft and tender; 
even the corneous ones, as the head and the legs, are then 
scarcely more than membranous, and are all bathed with 
a fluid, which, before the moult, intervenes between the 
two skins, and facilitates their separation b : and it is 
only after some hours, or in some cases even days, du- 
ring which it lies without motion, that this humidity eva- 
porates, all its parts become consolidated, and it reco- 
vers its strength sufficiently to betake itself to its wonted 
food. Its colour, too, is usually at first much paler than 
before, and its markings indistinct, until their tints have 



a Entwickelungsgeschichte, &c. 34, 88. Swammerdam on the con- 
trary affirms, that " on the hinder part of the cast skin where it is 
twisted and complicated, whoever accurately examines the skin it- 
self may still observe the coat that was cast by the intestmum rectum, 
Ubisupr. 136. col. a. 

b N. Did. d'ffist. Nat. vi. 290. 



STATES Ol- INSECTS. J 99 

been enlivened by exposure to the air, when they become 
more fresh, vivid, and beautiful to appearance than ever. 
When a few meals have invigorated its languid powers, 
the renovated animal makes up for its long abstinence 
by eating with double voracity. 

A similar preparatory fast, and succeeding state of 
debility, accompany every change of the larva's skin. 
Each time except the last, the old skin is succeeded by 
a new one, with few exceptions, similar to the one it has 
discarded. Previously to the final change, which discloses 
the pupa, it quits the plant or tree on which it had lived, 
and appears to be quite unsettled, wandering about and 
crossing the paths and roads, as if in quest of some new 
dwelling. It now abstains from food for a, longer time 
than before a common moult, empties itself copiously, 
and as I have just said, if Swammerdam and Bonnet are 
to be depended upon, casts the skin that lines the sto- 
mach and intestines, as well as that of the Tracheae. 

I have observed above, that all larvae, with few excep- 
tions, change their skins in the manner that I have de- 
scribed. These exceptions are principally found in the 
order Diptera, of which those of the Linnean genera 
Musca, (Estrus, and probably all that, like the maggot 
of the common flesh-fly, have membranous contractile 
heads, never change their skin at all, not even prepara- 
tory to their becoming pupae. The skin of the pupa, 
though often differing greatly in shape from that of the 
larva, is the same which has covered this last from its 
birth, only modified in figure by the internal changes that 
have taken place, and to which its membranous texture 
readily accommodates itself The larvae of* the Dipte- 
rous genera Tipula, Cidej^ and those which have corne- 



200 STATES OF INSECTS. 

ous heads, like other larvae change their skins several 
times previously to becoming pupee a . The grubs, also, 
of bees, wasps, ants? and probably many other Hymeno- 
ptera, do not change their skin till they assume the pupa, 
nor the larva of the female Coccus b . 

If you feel disposed to investigate the reasons of that 
law of the Creator which has ordained that the skins of 
the higher animals shall be daily, and imperceptibly, and 
as it were piece by piece renewed, while those of insects 
are cast periodically and simultaneously, — the proximate 
cause must be sought for in the nature of the two kinds 
of skin, the one being more pliable and admitting a 
greater degree of tension than the other, and being so 
constructed as to scale off more readily. If, ascending 
higher, you wish to know why the skins of insects are so 
differently circumstanced from our own, the most appa- 
rent reason is, to accommodate the skin to the very rapid 
growth of these animals, which a gradual and slower 
change would have impeded too much, or the skin have 
suffered constant dilapidation and injury; therefore their 
Beneficent Creator has furnished them with one which 
will stretch to a certain point, and during a certain period, 
and then yield to the efforts of the inclosed animal, and 
be thrown aside as a garment that no longer fits the 
wearer. 

viii. And this leads me to a subject to which I am de- 

a Reaum. iv. 604. 

b Ibid. 364. N. Diet. d'Hist. Nat. xx. 365. Huber Fourmis 78. 
M. Huber does not say expressly that the grubs of ants do not change 
their skin ; but his account seems to imply that they change it only 
previously to their metamorphosis. 



STATES OF INSECTS. 201 

sirous now to bespeak your attention, — the Growth, I 
mean, and size of Insects in this state. As to size, larvae 
differ as much as insects in their perfect state : these last, 
however, never grow after their exclusion from the pupa, 
while larvae increase in bulk in a proportion, and often with 
a rapidity, almost without a parallel in the other tribes of 
animals. Thus Lyonnet found, that the caterpillar of 
the great goat-moth (Cosstis ligniperda F.) after having 
attained its full growth is at least 72,000 times heavier 
than when it was first excluded from the egg a ; and of 
course had increased in size in the same proportion. 
Connected with the size of larvae, is the mode in which 
their accretion takes place. This, with respect to the 
more solid parts, as the head, legs, &c, is not, as in other 
animals, by gradual and imperceptible degrees, but sud- 
denly and at stated intervals. Between the assumption 
of a new skin and the deposition of an old one, no in- 
crease of size takes place in these parts, while the rest of 
the body grows and extends itselfj till, becoming too big 
for these solid parts, nature restores the equilibrium be- 
tween them by a fresh moult b , in which the augmenta- 
tion of bulk, especially in these parts, is so great, that we 
can scarcely credit the possibility of its being cased in so 
small an envelope. Malpighi declares, that the head of 
a silk-worm that has recently cast its skin is four times 
larger than before the change c . It is very probable, 
also, that when the outer skin becomes rigid, it confines 
the body of the larva within a smaller compass than it 
would expand to if unconfmed, so that, when this com- 
pression is removed, the soft and elastic new integu- 

a Lyonnet 11. h JV. Diet. d'Hist. Nat. vi. 290. 

e He BombycihiiS) 68. 



202 STATES OF INSECTS. 

ment immediately swells out, and the animal appears all 
at once much larger than it was before the moult. In 
fact, the proximate cause of the rupture and rejection of 
the old skin is the expansion of the included body, which 
at length becomes so distended as to split its envelope, 
aided, indeed, as before described, by the contortions of 
the creature itself. 

The larvae most notorious for the rapidity of their 
growth are those of Musca carnaria and other flesh-flies : 
some of which Redi found to become from 140 to more 
than 200 times heavier in twenty-four hours a : an increase 
of weight and size in so short a time truly prodigious, 
but essential for the end of their creation — the rapid re- 
moval of dead and putrescent animal matter. As the 
skins of these larvae are never changed, we may conclude, 
if the cause of the change of skin in other larvae above 
surmised be accurate, that their skins are more contrac- 
tile and capable of a greater degree of tension than those 
of larvae that are subject to moulting. And two peculi- 
arities observable in them confirm this idea : in the first 
place, their head is not hard and corneous, as that of 
the others, but capable of being shortened or lengthened ; 
and in the next, their breathing-pores are not in the sides, 
but at the extremities of the body, while in the moulting 
larvae there are two in almost every segment, which must 
form so many callous points that impede the stretching 
of the skin to the utmost. The hairs, spines, and tuber- 
cles, that are so often found on caterpillars, must also 
form so many points of resistance that prevent that full 
extension of the integument which it might otherwise 
admit. 

3 Opiisc, i. 27- 



STATE* OF INSECTS. 203 

There is not always that proportion between the size 
of larvae and of the insects that proceed from them that 
might have been supposed, some small larvae often pro- 
ducing perfect insects larger than some of those proceed- 
ing from such as are of greater size. 

ix. As insects often live longest in the state we are 
treating of, I shall say something next upon the age of 
larvae, or the period intervening between their exclusion 
from the egg and their becoming pupae. This is exceed- 
ingly various, but in every case nicely adapted to their 
several functions and modes of life. The grubs of the 
flesh-fly have attained their full growth, and are ready to 
become pupae, in six or seven days ; the caterpillar of Ar- 
gynnis Paphia, a butterfly, in fourteen days ; the larvae of 
bees in twenty days ; while those of the great goat-moth 
(Cossus ligniperda) and of the cockchafer (Melolontha vul- 
garis) live three years, or at least survive three winters, be- 
fore the same change. That of another lamellicorn beetle 
(Oryctes nasicornis F.) is said to be extended to four or 
five ; that of the wire- worm (Elater segetum) to five. 
That of the stag-beetle [Lucanus Cervus) is affirmed by 
Rosel to be extended to six years ; but the most remark- 
able instance of insect longevity is recorded by Mr. Mar- 
sham in the Linnean Transactions a . A specimen of Bu~ 
prestis splendida, a beautiful beetle never before found in 
this country, made its way out of a deal desk in an office 
in London in the beginning of the year 1810, which had 
been fixed there in the year 1788 or 1789; so that ac- 
cording to every appearance it had existed in this desk 

3 Linn. Trans, x. 399. 



204 STATES OF INSECTS. 

more than twenty years. Ample allowance being made 
for its life as a pupa, we may conclude that it had existed 
as a larva at least half the above period. The grubs of 
the species of the genus Cynips L. attain their full size 
in a short time ; but they afterwards remain five or six 
months in the gall before they become pupae a . 

With few exceptions it may be laid down, that those 
larvae which live on dead animals, in fungi, in dung, and 
in similar substances, are of the shortest duration in this 
state ; and that those which live under the earth, on the 
roots of grass, &c. and in wood, the longest: the former 
becoming pupae in a few days or weeks, the latter requir- 
ing several months, or even years, to bring them to ma- 
turity. The larvae which live on the leaves of plants 
seem to attain a middle term between the one and the 
other, — seldom shorter than a few weeks, and rarely 
longer than seven or eight months. Aquatic larvae ap- 
pear to be subject to no general rule: some, as the larvae 
of Gnats, becoming pupae in two or three weeks; and 
others, as those of the Ephemerce, which are thus com- 
pensated for their short life as flies, in as many years b . 
The cause of all these differences is obviously dependent 
on the nature of the food, and the purposes in the eco- 
nomy of creation to which the larvae are destined. 

x. The last part of the history of larvae relates to their 
Preparations for assuming the pupa state. When they 
have acquired their full size, after having ceased to take 

a N. Diet. d'Hist. Nat. vii. 129. 

b As the larvae of Ephemeras usually live in the submerged part of 
the banks of rivers, perhaps they may be regarded as following the 
economy of subterranean terrestrial larvae. 



STATES OF INSECTS. 205 

food, by a copious evacuation they empty the intestinal 
canal, even rejecting the membrane that lines it and the 
stomach a ; their colours either change totally, or fade ; 
and they make themselves ready for entering upon a 
new stage of their existence. Some merely rest in a 
state of inactivity in the midst of the substances in which 
they feed, as if conscious of their inability to select any 
safer abode. Of this description are most Coleopterous, 
Hymenopterous, and Dipterous larvae, that feed under 
ground, or in the interior of trees, fruits, and seeds. 

But a still larger tribe, those which feed on leaves, ani- 
mals, &c. act as if more sensible of the insecurity of this 
to them important epoch. They are about to exchange 
their state of vigour and activity for a long period of death- 
like sleep. The vigilant caution which was wont to guard 
them from the attack of their enemies will be hencefor- 
ward of no avail. Destitute of all the means of active 
defence, their only chance of safety during their often 
protracted night of torpor must arise from the privacy of 
their place of repose. About this, therefore, they exhibit 
the greatest anxiety. Many, after wandering about as if 

a A caterpillar nearly answering to the description of that of 
Bombyx camelina, which I found upon the hazel, after a few days 
produced sixteen grubs of some Ichneumon. At first these grubs were 
green, but they became gradually paler ; and after a day or two be- 
came pupae. But I mention this circumstance here for another rea- 
son : upon examining them after this last occurrence, I observed that 
they adhered to the lid of the box in which I kept the larva, arranged 
somewhat circularly ; and at a little distance from the anus of each 
was a pea-green mass, consisting of about eight oval granules, which 
appeared like so many minute eggs. These were the excrement eva- 
cuated by each grub previously to its becoming a pupa. The appear- 
ance of this little group, with their verdant appendage, formed a cu- 
rious spectacle : they are still pupa?, July 30, I82g. 



20G STATES OF INSECTS, 

bewildered, retire to any small hole on the surface of the 
earth, covering themselves with dead leaves, moss, or the 
like, or to the chinks of trees, or niches in walls and other 
building's, or similar hiding-places. Many penetrate to 
the depth of several inches under ground, and there form 
an appropriate cavern by pushing away the surrounding 
earth; to which they often give consistence by wetting it 
with a viscid fluid poured from the moutlv. The larvae 
of other insects undertake long and arduous journeys in 
search of appropriate places of shelter. Those of flesh- 
flies, now satiated with the mass of putridity in which 
they have wallowed, leave it, and conceal themselves in 
any adjoining heap of dust. The grubs of the gad-fly 
( CEstrns) creep some of them out of the backs of cattle, 
in tumours of which they have resided, and suffer them- 
selves to fall to the earth ; while others, which have fed 
in the stomach of horses, quit their hold, and by a still 
more extraordinary and perilous route are carried through 
the intestines the whole length of their numerous circum- 
volutions, and are discharged at the anus. And without 
enumerating other instances, various aquatic larvee, as 
that of a common fly [Elophiliis pendukis), &c. leave the 
water, now no longer their proper element, and betake 
themselves to the shore, there to undergo their metamor- 
phosis. 

Most of these, having reached their selected retreat, 
require no other precaution ; but another large tribe of 
larvae have recourse to further manoeuvres for their de- 
fence before they assume the pupa. Those of the aphi- 
divorous flies (Sz/rphus F. &c), of the various lady-birds 
(CoccinellaL.), and tortoise-beetles (Cassida L.), &c. fix 
themselves by the anus with a gummy substance to the 



STATES OF INSECTS. 207 

leaves or twigs under which they propose to conceal them- 
selves during their existence in that state. Others previ- 
ously suspend themselves by a silken thread fixed to the 
tail, or passing round the body ; by which also, when become 
pupae, they are afterwards pendent in a similar position ; 
and lastly, a very great number of larvae wholly inclose 
themselves in cases or cocoons, composed of silk and va- 
rious other materials, by which during their state of re- 
pose they are protected both from their enemies and the 
action of the atmosphere. As these two last-mentioned 
processes are extremely curious and interesting, I shall 
not fear tiring you by entering into some further detail 
respecting them : ex-plsdning first the mode by which lar- 
vae suspend themselves, both before and after they are 
become pupae, by silken threads ; and next, the various 
cases or cocoons in which others inclose themselves, and 
their manner of operating in the formation of them. 

1 . The larvae which suspend themselves and their pu- 
pae, with the exception of the tribe of Alucitce, and some 
Geometrce of the family of G. pendidaria, punctaria, &c. 
are almost all butterflies a . No others follow this mode. 
They may be divided into two great classes — those which 
suspend themselves perpendicularly by the tail, and those 
which suspend themselves horizontally by means of a 

a Except some species of Potyommatus Latr. (Thecla, ArgynnisF '.), 
P. Argiolus, Cory don, &c, and Hesperia Rubi, Betuice F., &c. Some 
of the larvae of the former become pupae within the stalk of some 
plant, or partly under the earth : those of the latter usually in a leaf 
to which the abdomen is fastened by various threads. These last 
are the rouleuses of the butterfly-tribe, living, like some moths, in 
leaves that they have rolled up. N. Diet. d'Hisi. Nat. xxiv. 499. 



208 STATES OF INSECTS. 

thread girthed round their middle. In both cases it 
should be observed, that the suspension of the pupa is 
the object in view ; but as the process is the work of the 
larva, this seems the proper place for explaining it. To 
begin with the^/zrs^ case. 

You are aware that all lepidopterous larvae have the 
faculty of spinning silk threads from their mouths, and 
it will readily occur to you that it is by means of these 
threads that they suspend themselves. But how ? How 
is a caterpillar to hang itself by the tail to threads spun 
from the mouth ? Even suppose this difficulty overcome, 
others still greater remain. Suppose the caterpillar to 
be suspended by its tail, — this is but a preparatory ope- 
ration, — what is required is, that the pupa shall hang in 
the same position : now when you take into consideration 
that it is incased within the skin of the larva, and without 
feet or other external organs; that it has to extricate it- 
self from this skin ; to hang itself in its place, and to de- 
tach the skin from the threads which hold it — this will 
appear no trifling task. Indeed at first view it seems 
impossible. Country-fellows for a prize sometimes amuse 
the assembled inhabitants of a village by running races 
in sacks : take one of the most active and adroit of these, 
bind him hand and foot, suspend him by the bottom of 
his sack with his head downwards, to the branch of a 
lofty tree ; make an opening in one side of the sack, and 
set him to extricate himself from it, to detach it from 
its hold, and suspend himself by his feet in its place. 
Though endowed with the suppleness of an Indian jug- 
gler, and promised his sack full of gold for a reward, you 
would set him an absolute impossibility : yet this is what 



STATES OF INSECTS. 209 

our caterpillars, instructed by a beneficent Creator, easily 
perform. Their manoeuvres I shall now endeavour to 
explain. 

When the caterpillar has selected the under-side of 
the leaf or other object to which it purposes suspending 
itself, its first process is to spin upon it a little hillock of 
silk consisting of numerous loosely interwoven threads ; 
it then bends its body so as to insinuate the anal pair of 
prolegs amongst these threads, in which, by a slight ex- 
ertion, the little crochets which surround them a become 
so strongly entangled as to support its weight with ease. 
It now suffers the anterior part of the body to fall down, 
and it hangs perpendicularly from its silken support with 
its head downwards. In this position it remains often for 
twenty-four hours, at intervals alternately contracting and 
dilating itself. At length the skin is seen to split on the 
back near the head, and a portion of the pupa appears, 
which by repeated swellings acts like a wedge, and ra- 
pidly extends the slit towards the tail. By the continu- 
ance of these alternate contractions and dilatations of the 
conical pupa, the skin of the caterpillar is at last collected 
in folds near the tail, like a stocking which we roll upon 
the ancle before withdrawing it from the foot. But now 
comes the important operation. The pupa, being much 
shorter than the caterpillar, is as yet at some distance 
from the silken hillock on which it is to be fastened ; it 
is supported merely by the unsplit terminal portion of 
the latteYs skin. How shall it disengage itself from this 
remnant of its case, and be suspended in the air while it 
climbs up to take its place ? Without arms or legs to 

b Plate XXIII. Fig. 1. a. 
VOL. Ill, P 



210 STATES OF INSECTS. 

support itself, the anxious spectator expects to see it fall 
to the earth. His fears, however, are vain ; the supple 
segments of the pupa's abdomen serve in the place ol 
arms. Between two of these, as with a pair of pincers, it 
seizes on a portion of the skin; and bending its body once 
more, entirely extricates its tail from it. It is now wholly 
out of the skin, against one side of which it is supported, 
but yet at some distance from the leaf. The next step it 
must take is to climb up to the required height. For this 
purpose it repeats the same ingenious manoeuvre, making 
its cast-off skin serve as a sort of ladder, it successively 
with different segments seizes a higher and a higher 
portion, until in the end it reaches the summit, where 
with its tail it feels for the silken threads that are to sup- 
port it. But how can the tail be fastened to them ? you 
ask. This difficulty has been provided against by Crea- 
tive Wisdom. The tail of the pupa is furnished with nu- 
merous little hooks pointing in different directions a , as 
well adapted to the end in view as the crochets of the 
larva's prolegs, and some of these hooks are sure to fast- 
en themselves upon the silk the moment the tail is thrust 
amongst it. Our pupa has now nearly completed its la- 
bours ; it has withdrawn its tail from the slough, climbed 
up it, and suspended itself to the silken hillock — manoeu- 
vres so delicate and perilous, that we cannot but admire 
that an insect which executes them but once in its life, 
should execute them so well : nor could it, as Reaumur 
has well and piously observed, had it not been instructed 
by a Great Master. One more exertion remains : it 
seems to have as great an antipathy to its cast-off skin, 

a Plate XXIII. Fie. 8. a. 



STATES OF INSECTS. 211 

as one of us should, when newly clothed after a long im- 
prisonment, to the filthy prison garments we had put off. 
It will not suffer this memento of its former state to re- 
main near it, and is no sooner suspended in security than 
it endeavours to make it fall. For this end — it seizes, 
as it were with its tail, the threads to which the skin is 
fastened, and then very rapidly whirls itself round, often 
not fewer than twenty times. By this manoeuvre it ge- 
nerally succeeds in breaking them, and the skin falls 
down. Sometimes, however, the first attempt fails : in 
that case, after a moment's rest, it makes a second, twirl- 
ing itself in an opposite direction ; and this is rarely un- 
successful. Yet now and then it is forced to repeat its 
whirling, not less than four or five times : and Reaumur 
has seen instances where the feet of the skin were so firmly 
hooked, that after many fruitless efforts the pupa, as if 
in despair, gave up the task and suffered it to remain a . 
After these exertions, it hangs the remainder of its exist- 
ence in this state until the butterfly is disclosed. 

We are now to consider the second mode of suspen- 
sion, in which larva? by means of a silken girth round 
their middle, fix themselves horizontally under leaves, &c. 
These follow the same process with that of those last de- 
scribed, in spinning a small hillock of silk to which they 
fasten their hind legs ; and if the operation concerned the 
larva state alone, this would be sufficient, as by means of 
this support, and of their prolegs, they could easily re- 
tain themselves in a horizontal position. But these lar- 

a Bonnet is of opinion that this twirling process is not with any 
view to get rid of the exuviae, but is caused only by the irritation oc- 
casioned by the spines of the skin of the caterpillar when they touch 
that of the pupa. CEuv. ii. 109. 

p 2 



212 STATES OF INSECTS. 

vse act as if they foresaw the assumption of a state in 
which they will be deprived of legs. It is the suspension 
of the forthcoming pupa that is the object in view ; and 
though this can be hung by the tail in the same way with 
those of the first class, yet it is plain that it cannot be re- 
tained in a horizontal position, which for some unknown 
reason is essential to it, without some support to its an- 
terior extremity. It is necessary for the larva, therefore, 
not only to fix its posterior legs amongst a collection of 
silken fibres, but to spin a girth of the same material 
round its body. This girth, though apparently of a sin- 
gle thread, will be found on examination to be composed 
of several, often as many as fifty or sixty ; and is fastened 
on each side of the body of the larva about the middle, 
to the surface under which it is placed. Three different 
modes of fixing these girths are adopted by the caterpil- 
lars of different butterflies. Some, as those of the com- 
mon cabbage-butterfly (Pieris Brassier), which have re- 
markably pliable bodies, bend them almost double on 
one side, then fix the thread and carry it over to the 
other in the same position, repeating this operation as 
often as is necessary. Others, as that of Lyccena Argus 
and many more of the Papiliones Rurales and JJrbico- 
Ice L., which have a short and more rigid body, after 
having bent the head on one side so as to fix one end of 
the thread, bring themselves into a straight position, and, 
by a manoeuvre not easily described, contrive to intro- 
duce the head under the thread, which they then bend 
themselves to fasten on the other side, pushing it to its 
proper situation by the successive tension and contrac- 
tion of their segments. But the most curious mode, 
though indeed that which seems most natural, is adopted 



STATES OF INSECTS. 213 

by the caterpillar of the beautiful swallow-tail butterfly 
[Papilio Machaon) and others of the same family. This 
first forms the loop which is to serve for its girth, and 
then creeps under it. But the difficulty it has to surmount 
is, to keep itself from being entangled in the fifty or sixty 
fine distinct threads of which the girth is composed, and 
to preserve them all extended so as to be able to intro- 
duce its body beneath them. For this purpose it makes 
use of the two first pair of its fore-legs, employing them 
as a woman does her hands in winding a skein of cotton, 
to collect and keep all the threads of its card unentangled 
and properly stretched ; and it is often with great diffi- 
culty, towards the end of the process, that it prevents 
them from slipping off. When a sufficient number of 
threads is completed, the animal bends its head between 
its legs, and insinuates it under the collected loop, which 
by its annular contraction it easily pushes to the middle 
of the body. 

In about thirty hours after the larva? which girth them- 
selves have finished their operations, the skin splits, and 
the pupa disengages itself from it by those contractions 
and dilatations of its segments which have been before 
described, pushing the exuviae in folds to the tail, by dif- 
ferent motions of which it generally succeeds in detach- 
ing them. One would have thought there would be con- 
siderable difficulty in slipping the skin past the girth; 
but this, according to Reaumur, seems to be easily ef- 
fected 3 . 

If you are desirous of witnessingfor yourself the manoeu- 
vres by which these curious modes of suspension are 

a For the above account see Reaum. i. Mem. x. xi. 



214 STATES OF INSECTS. 

effected, you may be readily gratified. It is only neces- 
sary to collect and feed until their metamorphosis the 
black spinous caterpillars of the common peacock-but- 
terfly ( Vanessa lo), which in most places may be found 
upon nettles, or those of the Pieris Brassicts, which swarm 
in cabbages or brocoli in every garden. The former will 
exhibit to you a specimen of vertical, the latter of hori- 
zontal suspension. It should be observed, however, that 
to hit the precise moment when these processes are go- 
ing on, it is necessary to feed a considerable number of 
the larvae of each kind; some one of which, if you watch 
them narrowly when they have attained their full growth, 
you will scarcely fail to surprise in the act. 

I must observe here, that although the vertical and 
horizontal are the two principal positions in which cater- 
pillars suspend themselves, yet that others are inclined at 
various angles; and some are attached with less art, ap- 
pearing only to be fastened by some part of their abdo- 
men to the body upon which they are fixed a . 

2. The larvae whose procedures I am in the next place 
to describe, are those which, previously to assuming the 
pupa state, inclose themselves in cases or cocoons of diffe- 
rent materials. For the sake of method, I shall divide 
these into two great classes : First, those which form their 
cocoons entirely or principally of silk; and secondly y 
those which form them chiefly of other substances. 

To begin with the Jirst. The larvae which inclose 
themselves in silken cocoons are chiefly of the Lepido- 
pterous tribes of Bombycidce and Noctuidce ; but a few 

* N. Diet. a" Hist. Nat. w. 591—. 



STATES OF INSECTS. 215 

Geometrce (G. papilioniaria, lactearia, &c); most of the 
Hymenoptera ; some Coleoptera, as certain of the weevil 
tribe (Hyper a Arator, Rumicis Germ.), and those bril- 
liant beetles frequenting aquatic plants constituting the 
genus Donacia F. ; the Neuropterous genera Hemerobius 
and Myrmeleon : Mycetophila and a few others in the 
Diptera ; and Pulex in the Aphaniptera fabricate cover- 
ings of the same material. In all, with the exception of 
Myrmeleon and Hemerobius (and perhaps Hypera Rumi- 
cis, &c. ?) which have their spinning apparatus at the 
extremity of the abdomen, the silken thread employed in 
forming these coverings proceeds from the middle part of 
the under-lip, as before explained ; and is in fact com- 
posed of two threads gummed together as they issue from 
the two adjoining orifices of the spinner. 

Of the larvas which inclose themselves in silk, the most 
familiarly known is the silk-worm : the cocoon of this 
consists exteriorly of a thin, transparent, gauze-like coat- 
ing, through the interstices of which can be seen an in- 
ner, smaller, oval ball of a more close and compact tex- 
ture. The whole is in fact composed of one single 
thread, but arranged in two distinct modes. To form 
the exterior envelope, which is merely the scaffolding by 
means of which the inner and more solid covering is con- 
structed, the caterpillar, after fixing upon a space between 
two leaves or twigs or angles suitable for its purpose, 
begins by glueing one end of its thread to one of the ad- 
joining surfaces. This thread it next conducts to another 
part and then fastens, repeating this process and inter- 
lacing it in various directions, until it has surrounded it- 
self with a slight and loosely spun netting. In the cen- 
tre of this, when contracted into a space sufficiently small, 



216 STATES OF INSECTS. 

it lays the foundation of the interior cocoon. Fixing it- 
self by its prolegs to some of the surrounding threads, 
it bends its body, and by successive motions of its head 
from side to side spins a layer of silk on the side oppo- 
site to it : when this is of the requisite thickness, the larva 
shifts its position, and repeats the same process in another 
quarter, covering each layer in turn with a new one 
until the interior cavity is reduced to the size desired. 
Thus, the silken thread which forms this new cocoon is 
not, as might have been supposed, wound circularly as 
we wind the thread of a ball of cotton; but backwards and 
forwards in a series of zigzags, so as to compose a num- 
ber of distinct layers. Malpighi could distinguish sjx of 
these layers a , and Reaumur suspects there is often a 
greater number b . The former found the length of the 
■thread -of silk composing them when wound off, without 
including the exterior case, to be not less than 930 feet c ; 
but others have computed it at more than a thousand d : 
consequently the threads of five cocoons united would be 
a mile in length. Estimating by the weight, — the thread 
of a pound of cocoons, each of which weighs about two 
grains and a half, would extend more than 600 miles e , 
and such is its tenuity, that the threads of five or six co- 
coons require to be joined to form one of the thickness 
requisite in the silk manufacture. It is the continuous 
thread of the inner cocoon which is most valuable ; the 
outer loose coating from its irregularity cannot be 



a Be Bombyc. 24. >> i. 498. 

c Be Bombyc. 43. a N. Bid. d'Hist. Nat. vi. 294. 

e Lesser. L. ii. 150, note 22. Boyle says an English lady found that 
the silk of a single cocoon would extend 300 English leagues or 900 
miles. But this must be a mistake. 



STATES OF INSECTS. 217 

wound off, and is known in commerce by the name ofjloss 
silk. 

Manoeuvres in their general principle similar to those 
of the silk-worm are followed by most of those larvae 
which inclose, themselves in silken cocoons. Many spe- 
cies, however, adopt variations in the mode of procedure 
all of which it would be tedious to particularize, but some 
of them are worth mentioning. The larvae of Tortrix 
prasinana, and other species of moths which form co- 
coons resembling a reversed boat, arrange their threads 
in layers, so as to construct two parallel walls gradually 
inclining towards the top and ends, where they finally 
force them to approach each other by means of an appa- 
ratus of silken cables a . And the larva of Saturnia Pavo- 
nia, though it forms the base of its flask-shaped cocoon by 
spinning like the silk-worm a number of interwoven zig- 
zags, places the threads which compose the interior fun- 
nel-like opening of the apex nearly straight, parallel to 
each other, and converging towards the same point in 
the centre b . 

These last, as well as almost all larvae, constantly re- 
main in the inside of the cocoon during its construction. 
But De Geer has given us the history of a minute cater- 
pillar of a species of moth [Tinea L.) which feeds on the 
under side of the leaves of the Rhamnus Frangula, or 
Black Alder, that actually weaves half of its cocoon on the 
outside. This cocoon, which is very small, is beautifully 
fluted, consisting of several longitudinal cords, with the 
intervals filled by fine net-work, and shaped like a re- 
versed boat c . The animal begins by laying the founda- 

a Reaum. i. 555—. h Plate XVIJ. Fig. 5. b. 

c De Geer i. t. xxxii./. 3—6. 



218 STATES OF INSECTS. 

tions of one of the ends of her cocoon, she adds new- 
threads to this small beginning, and so proceeds. As 
the work advances she retreats backwards, and her body 
is situated nearly in the same line with the cocoon she 
has begun, and quite out of it ; she only touches with her 
head and legs its anterior margin. When half the co- 
coon, or rather of its exterior layer, is finished, she sus- 
pends her operations for some moments. She then for 
the first time introduces her head into this demi-cocoon, 
and turns herself in it by doubling her supple body, and 
passing one part over the other, so that at last she ma- 
nages to bring her tail into the pointed end of the cocoon, 
the head and the anterior half of her body remaining 
without. Thus situated, she commences her operations 
afresh. At a distance from the margin of the demi-co- 
coon, equal to its length, she begins to spin the pointed 
end of the other moiety, the length of her body serving 
her as a measure that enables her to begin at the proper 
distance from it. This new portion she spins in the same 
manner as the other ; but as she is prevented by the demi- 
cocoon in which the posterior part of her body is lodged 
from retreating backwards, she contracts her body more, 
which answers the same purpose. When the new work 
is so advanced that she can no longer contract her body, 
she bends the anterior part of it considerably, and re- 
verses her head. When the distance between the mar- 
gin of the two halves of the cocoon is very small, so as no 
longer to admit the head between them, in order to unite 
them she is obliged to have recourse to another manoeu- 
vre. Withdrawing her head, she extends silken longitu- 
dinal threads between the two margins, and thus unites 
them. This part is more clumsy, and not so regular as 



STATES OF INSECTS. 219 

the rest of the cocoon, so that the point of union is always 
discoverable. These caterpillars do not always divide 
the cocoon into two equal portions, for often they will 
finish three quarters of the cocoon before they enter it, 
and begin at the other end a . 

The general rule is, — that each larva spins for itself a 
separate cocoon ; but amongst those of Arctia chrysorhea 
and others which live in society, two or three sometimes 
begin their operations so close together that they are 
under the necessity of forming one common cocoon, which 
serves for a covering to the whole number. The same 
thing happens to silk- worms, the double or treble cocoons 
of which are called Dupions by the breeders. The larvae 
of some Ichneumons, besides forming each its separate 
cocoon, spin a joint cottony covering for the whole 5 , 
which is effected thus: — After they leave the caterpillar 
they have devoured, they fix themselves side by side at a 
little distance from it, and begin to spin each a cocoon ; 
and in order to defend its end and side that is not covered 
by others, they spin further an envelope of loose silk, 
and thus this exterior covering is formed. 

The size, figure, colour, substance, and texture of 
silken cocoons are extremely various. Their size indeed 
is usually proportioned to that of the included larva or 
pupa ; yet it is by no means always so. Some large ca- 
terpillars spin cocoons so small, that the observer can 
hardly conceive how they can be contained in so narrow 
a compass : Eriogaster Cataoc is a moth of this descrip- 
tion c . And others smaller in size lodge themselves in 

a De Geer i. 463—. 

b Reaum. ii. Mem. xi. Comp. De Geer ii. 162. Reaum. ii. 424. 

e JB. Catax — Pupa arete folliculata. Fab. 



220 STATES OF INSECTS. 

apartments apparently much more spacious than neces- 
sary. The transparent hammock-like cocoons of Hepi- 
alus Humuli and Arctia villica, two other moths, would 
contain several of their pupae. I possess one in which 
the pupa is suspended in the centre, that is ten times its 
size, and not very short in dimensions of that of Attacus 
Papilla^ a giant silk-moth. The largest cocoon I ever 
read or heard of, is that thus described by Mr. Hobhouse 
in his Travels: " Depending," says he, "from the boughs 
of the pines, near the Attic mountain Parties, and stretch- 
ing across from tree to tree so as to obstruct our passage, 
were the pods, thrice as big as a turkey's egg ! and the 
thick webs of a chrysalis, whose moth must be far larger 
than any of those in our country." a If this statement 
is correct, and I am not aware that there is any reason 
for doubting it, the cocoon must be vastly larger than the 
pupa, or the moth it produced would far exceed in size 
any yet known. Perhaps, however, as this gentleman is 
probably no entomologist, what he took for a cocoon 
might be a nidus, in which many larvae were associated, 
of the nature of those formerly described b . 

With regard to figure, the majority are like those of 
■the silk-worm, of a shape more or less oval or elliptic : 
some, however, vary from this. That of Lasiocampa 
Riibi is oblong. I have one from New Holland some- 
what resembling an acorn, fixed to the twigs of some tree 
or shrub, of a very close silk, and covered by a circular 
operculum, which the animal pushes off when it assumes 
the imago; this is ovate or conico-ovate; others again are 
globose c ; others are conical d , as that of Gastropacha 

a Travels in Greece, 285. »> See above, Vol. I. p. 476—. 

1 Merian Surinam, t. xv. A Reaum. ii. t. xxiii./. 5. 



STATES OF INSECTS. 221 

quercifolia ; others almost fusiform a (Odenesis potaioria). 
Reaumur received one from Arabia which was nearly 
cylindrical b . Those of T. prasinana before noticed, and 
many other Tortrices, are shaped like a reversed boat c ; 
that of Saturnia Pavonia and others of the same tribe, 
like a Florence flask with a wide and short neck. The 
cocoon of Lygcena Filipendula: resembles a grain of bar- 
ley. Another cocoon in my cabinet, of very slight net- 
work, is shaped something like an air-balloon. But the 
most remarkable one for its form and characters, is one 
that I received from the rich cabinet above quoted. This, 
which is of an unusually close texture, is suspended by 
a thread more than two inches long from the point of a 
leaf; it then swells into a perfect cone, at the base about 
four-fifths of an inch in diameter and half an inch in 
length, and covered with scattered setiform appendages : 
from the centre of the base projects a large hemispherical 
protuberance, which terminates in a long stalk, much 
thicker than the thread that suspends the cocoon. There 
is commonly no difference between the shape of cocoons 
spun by larvae which are to give birth to different sexes of 
the same species. The silk-worm cocoons, however, 
which will produce male moths, have more silk at the 
ends, and consequently are more round than those which 
are to produce females : but the difference is not strik- 
ing;. 

The most usual colour of silken cocoons is white, yel- 
low, or brown, or the intermediate shades. The whites 
are very pure in the general envelope of some species 
of Ichneumonidce, and yellows often very brilliant. But 

a Sepp. iv. t. viii./. 5. b Reaum, i. t. xliv./. 2. 

c Plate XVII. Fig. 7. 



222 STATES OF INSECTS. 

besides these more general colours, some cocoons are 
black a , some few blue or green, and others red b . Some- 
times the same cocoon is of two different colours. Those 
of certain parasites of the tribe of Ichnenmones minuti L. 
the motions of one of which I noticed on a former occa- 
sion c , are alternately banded with black or brown and 
white, or have only a pale or white belt in the middle, 
which gives them a singular appearance. In both cases 
the difference in colour depends upon the different tints 
with which the silky gum is imbued in the reservoirs : 
the first portion of it is white, and with this the larva 
first sketches the outline of its cocoon, and then thickens 
the layers of silk considerably in those parts where the 
white bands appear : when these are finished, its stock 
of white silk is exhausted, and the remainder of the inte- 
rior of the cocoon is composed of brown silk d . The cir- 
cular operculum above mentioned as covering an acorn- 
shaped cocoon, is paler than the latter, and also orna- 
mented by a zone within the margin of deep brown. 
The pale cocoon also of Attacus Paphia is veined with 
silk of a deep red. 

I have very little to say on the substance of the silk of 
cocoons. Though that of the silk- worm is composed of 
such a slender thread, that of many others is still finer, 
scarcely yielding in tenuity to the spider's web. On the 
other hand, the silk of the cocoons of Saturnia Pavonia 
and of several foreign species is as thick as a hair. 

With regard to the texture of their cocoons— in some, 
as in that of the silk-worm, the threads are so slightly 

3 I have a black one from Mr. Francillon's cabinet. 

b W. Diet. d'Hist. Nat. vi. 294. 

See above, Vol.. II. p. 298—. d Reaum. ii, 436. 



STATES OF INSECTS. 223 

glued to each other, as to separate with facility ; but in 
that of the emperor-moth just mentioned they are inti- 
mately connected by a gummy matter, furnished, as 
Reaumur conjectures, from the anus a , with which the 
whole interior of the cocoon is often plastered. Some, 
as that of the silk-worm, are composed of an exterior 
loose envelope, and an inner compact ball ; others have 
no exterior covering, the whole cocoon being of an uni- 
form and thick texture. The larva of Cossus Robinice 
Peck, in spinning its cocoon, makes the end next the 
opening to the air, by which the imago is to emerge, of a 
slighter texture than the rest of it b . The exterior case 
is sometimes, as in Laria pudibunda, very closely woven, 
so as to resemble a real cocoon c : its form is usually 
adapted to that of the inner one ; but in some which fix 
them under flat surfaces (Laria fascelhia, Callimorpha 
Cqja,) it resembles a hammock d . Cocoons of a close 
texture have generally no orifice in any part ; but that of 
Eriogaster lanestris is spun with openings, as if bored 
from without, the use of which, however, does not seem 
to have been ascertained e . 

Many silken cocoons are of so close a fabric, as, when 
finished, entirely to conceal the included insect; but a 
very considerable number are of a more open texture, 
composed of a much smaller quantity of silk, and that 
woven so loosely, that the larva or pupa may always be 
discovered through it. Of this description are the co- 
coons of Hypogymna dispar, Arctia Saltcis, &c, which 
consist only of a few slight meshes. Those of some others 

* Reaum. i. 503. b Peck on Locust-tree Insects, 69. 

c Bonnet ii. 260. d Sepp. iv. t.ii.f. 4. 

e Brahm. Ins. Kal. 289. 



224< STATES OF INSECTS. 

resemble gauze or lace a . Of the first description is one 
in my cabinet before alluded to, shaped somewhat like 
an air-balloon; the meshes are large and perfectly square. 
The pupa hangs in the centre, fixed by some few slight 
threads which diverge from it to all parts of the cocoon — 
so that it looks as if it was suspended in the air, like 
Mahomet's coffin, without support. Of the second de- 
scription is a black one with very fine and nearly circular 
meshes : the threads that form these are thick, and seem 
to be agglutinated. In our own country, the cocoons of 
some beetles, as ofcHypera Arator, Galeruca Tanaceti,and 
of some little Tinece, also resemble gauze. Many of the 
larvae, however, which spin these cocoons, whose thin- 
ness is probably attributable to the smallness of their 
stock of silk, seem anxious for a more complete conceal- 
ment ; and therefore commonly either hide them between 
leaves tied together, in some with a certain regularity, 
in others without art b ; or thicken their texture, and 
render it opaque, by the addition of grains of earth c , 
or of other materials with which their bodies sup- 
ply them. These are principally of two kinds. The 
larvae of Lasiocampa Neustria, Arctia Salic is, &c. after 
spinning their cocoons, cast from their anus three or four 
masses of a soft and paste-like matter, which they apply 
with their head all round the inside of the cavity ; and 
which, drying in a short time, becomes a powder that 
effectually renders it opake. This is not, as might be 
conjectured, an excrement, but a true secretion, evidently 

a Plate XVII. Fig. 8. 

b The thick cocoons of Atiacus Paphia, Polyphemus, &c. are also 
thus fastened between leaves. 
c Merian Europ. ii. /. ix. 



STATES OF INSECTS. 225 

intended for this very purpose : and, according to Reau- 
mur, a similar powder, but white, derived from the vari- 
cose intestines, is used by the caterpillars of Gastropacha 
quercifolia, &c. a The other material, which is still more 
frequently employed, and which is occasionally mixed 
with the former, is the hair which every one has observed 
to cover so thickly the bodies of some caterpillars. This, 
after spinning a sufficient envelope, they tear, or in some 
instances cut off with their mandibles, and distribute all 
round them, pushing it with their head amongst the in- 
terstices of the silk, so as to make the whole of a regular 
thick texture. After this process, which leaves the body 
completely denuded, and often seems to give them great 
pain, they conclude by spinning another tissue of slight 
silk, in order to protect the forthcoming pupa from the 
surrounding prickly points. It should be observed, how- 
ever, that though many hairy larvae, as those of Noctua 
Aceris, Arctia Caja, and others, employ their hairs in the 
composition of their cocoons, the rule is not general, 
several never making any such use of them. Nor do all 
that do so employ them distribute them in the same man- 
ner as those above described, which rarely attempt to 
arrange them in any regular position. Reaumur has no- 
ticed a small hairy caterpillar that feeds on lichens, which 
is more methodical : this actually places its hairs upright, 
side by side, as regularly as the pales in a palisade, in 
an oval ring around its body, connecting them by a slight 
tissue of silk, which forces them to bend into a sort of 
roof at the top ; and under this curiously-formed cocoon 
assumes its state of pupa b . Some larvae make so much 

a Reaum. ii. 284. b Ibid. i. 524. 

VOL. III. O 



226 STATES OF INSECTS. 

hair and so little silk enter into the composition of their 
cocoons, that on the first inspection they would be pro- 
nounced wholly composed of it a ; others, thickening the 
interior of their cocoon with hair, line the whole with a 
viscid matter like varnish b . 

The larvee of some saw-flies (Tenthredo L.) are re- 
markable for inclosing themselves in a double cocoon, in 
which the inner is not, as in the silk-worm &c, connected 
with the outer, but perfectly distinct from it. Some spe- 
cies, as T. Rosce {Cryptus Jur.), which have but a small 
stock of silk, compose the outer cocoon of thick silken 
cords crossing at right angles, and forming an oval net; 
which at the same time that it protects them effectually 
from the ants, which are always ready to attack them, de- 
mands much less silk than a covering of a closer texture. 
But the tender nymph itself requires to be inclosed in a 
case of a softer and more delicate substance ; and accord- 
ingly the inner cocoon is composed of fine silk, woven 
so closely that the threads are scarcely perceptible under 
a microscope c . Reaumur mentions a hymenopterous 
larva belonging to Latreille's Fossores (Sphex L.) which 
thickened its cocoon with the legs, wings, and other relics 
of the flies which it had devoured d : trophies — like the 
drinking- cups of some savages, made of the skulls of their 
enemies, or the skull -pyramid near Ispahan — of its 
powers of devastation. 

It is a general rule, that those larvae which spin co- 
coons, never in ordinary circumstances become pupae 
without having thus inclosed themselves. An exception, 
however, is met with in the larva of a species of ant no- 

a Bonnet ii. 297. b Ibid. ix. 181. 

c Reaum. v. 102. <> Ibid. iy. 269. 



STATES OF INSECTS. 227 

ticed by De Geer (Formica fusca L.), some of the indi- 
viduals of which inclose themselves in cocoons; while 
others neglect this precaution, and undergo their meta- 
morphosis uncovered a . Rbsel also made nearly the 
same observation on the larva of the flea b . 

I must say something with regard to the situation, 
often very remote from their place of feeding, in which 
larvae fabricate their cocoons. A very considerable num- 
ber, probably the majority, form them either partially 
(Arctia lubricipeda) or wholly under ground; others 
beneath dead leaves, moss, or in the chinks of the trees ; 
others within the wood in substances on which they 
have fed ; the larva of Cossus leaves in these a communi- 
cation with the open air by which the imago emerges ; 
and a large number attach them to the leaves and 
branches of trees and plants ; the cocoon of Donatio fas- 
ciata (?) is fastened by one side to the roots or surculi of 
Typha latifolia. There is usually nothing very remark- 
able in the mode of fixing them, the exterior threads 
being merely gummed irregularly to different portions of 
the objects which support them. But some effect this with 
greater art. I have one from New Holland, very long, 
which is suspended from a twig by a long riband, as it 
were, which entirely girths the twig. The larva of the 
magnificent silk-moth, Attacus Paphia, actually forms a 
solid silken stalk to its cocoon, an inch and half in length 

a De Geer ii. 1084. Comp. Ray Hist. Ins. Praef. xi. It is the opi- 
nion of M. P. Huber, that in this case the naked pupa? are deprived 
of their cocoons by the neuters : he states, indeed, that he has often 
seen them pulled off by them, and also by those of F. cunicularia j 
and he seems to think that these larvae are never developed. Mceurs 
des Fourmis, 84. note 1. 

b II. viii. 16. 

o 2 



228 STATES OF INSECTS. 

and a line in diameter, fastened by the other extremity 
to a twig, which it closely surrounds as if with a ring, 
at first sight resembling a fruit of a very singular ap- 
pearance a . I have specimens of this cocoon with both 
stalk and ring. A bell-shaped cocoon fastened by a foot- 
stalk, but of softer consistence, to a blade of grass, found 
by Mr. Sheppard, I can also show you ; and my friend 
Mr. Wilkin had a similar one out of the late Mr. Hud- 
son's collection. Most larvae spin their cocoons in soli- 
tude : some of those, however, which live in society do it 
close together under their common tent. 

There are other cocoons that should be noticed here, 
such as those formed by the larva of Zygcena Filipejidulo', 
and some Bo?nbyces, saw-flies (Tenthredo L.), and bee- 
tles [Curculio, Donacia F.), &c. These are formed of 
a substance which seems more analogous to gum than 
silk, yet furnished from the silk reservoirs, and usually 
present the appearance externally of parchment or mem- 
brane. That of the insect first mentioned is coated, 
however, with a slight interior silken lining; as indeed 
are almost all cocoons, of whatever substance. 

The second class, into which I have divided larvae that 
inclose themselves in cocoons, includes those which form 
their coverings not solely or principally of silk, but in 
which other materials are mixed more or less. The co- 
coons of some of these larvae are merely composed of b, 
few leaves slightly tied together, either irregularly, or ar- 
ranged, particularly when they are of a linear figure, with 
considerable symmetry. The grubs of many beetles, as of 

a Linn. Trans, vii. t. ii.f. 5, 6. 



STATES OF INSECTS. 229 

the rose-beetle, Cetonia aurata, &c, prepare themselves a 
cocoon, composed of earth, pieces of rotten wood, and any 
substances within their reach; which they fasten together 
with a glutinous secretion. The same material is employed 
by others in forming a cocoon wholly of earth; which 
is sometimes, as that of the stag-beetle, Lucanus Cer- 
vus, exceedingly hard ; at others, as that of some moths, 
Noctua ambigiia, &c, so slight as to fall to pieces as soon 
as touched a . Other cocoons are formed of grains of 
earth. Reaumur has given a very interesting account of 
the procedures of a larva in repairing one of these co- 
coons, from which he had broken off the top when just 
completed. Without quitting the interior of the walls 
that remained, it put out its head from the breach, and 
for more than an hour employed itself in selecting one 
by one grains of earth, which it conveyed with its mandi- 
bles and deposited within its case : it next spun all round 
the opening threads of silk, to which it attached grains 
of earth taken from the previously-stored heap, uniting 
them compactly by means of other silken threads. After 
employing three hours in this laborious process, the in- 
dustrious little mason had reduced the diameter of the 
breach to a few lines. Reaumur was very curious to 
know how it would fill up this orifice, which would no 
longer admit the protrusion of its head outside the walls, 
as in its previous operations. He concluded, that while 
the rest of the cocoon was exteriorly formed of earth, 
this opening would be merely closed with silk. He was 
mistaken, however: the artist knew how to vary its 

a Wien. Verz. I possess a cocoon of this kind from New Hol- 
land, even now quite solid, and retaining its form. No silk appears 
to have been used in its composition. 



230 STATES OF INSECTS. 

manoeuvres, and make its vault of one uniform texture. 
It spun across the opening a little net of silk, between the 
meshes of which it thrust grains of earth so dexterously 
that they projected as far as the outer surface, retained 
there probably by silken lines previously attached and 
fastened within. It then finished its habitation by forti- 
fying the inside of the orifice with another layer of earth a . 
The ant-lion [Myrmeleoii) spins a globular cocoon with 
its anus, which it covers with grains of sand b . One that I 
took in the forest of Fontainebleau, in the quarry that pro- 
duces the crystallized sandstone called the Fontainebleau 
fossil, was covered with large and shining grains. Instead 
of the grains of earth or sand employed by these larvae, 
those of another tribe substitute grains of stone detached 
from the softer walls, upon whose lichens they previously 
feed, which they unite into solid oval cocoons c . Those 
of a fourth form their cocoons of patches of short moss 
arranged with the roots downwards, and forming a vault, 
as it were, of verdant turf, admirably adapted for con- 
cealment d . The larvae of some moths form their cocoons 
of irregular pieces of bark tied together with silk, and 
resembling when completed a knotty protuberance of the 
twig on which they are fixed. That of Pyralis tubercu- 
lana constructs a pannier-shaped one of the parenchyma 
of the leaves of plants e . 

All these cocoons, however, must yield in point of 
singularity of construction, materials, and ingenuity, to 
one formed by a small caterpillar, described by the illus- 
trious naturalist lately quoted, which feeds upon the oak. 
This cocoon is wholly composed of small rectangular 

» Reaum. i. 579. h Ibid. vi. 368. * Ibid. i. 542. 

d Ibid. 543. E Linn. Trans, i. 196. 



STATES OF INSECTS. 231 

strap-shaped pieces of the fine upper skin, or epidermis 
of the twig upon which it rests, regularly fastened to each 
other in a longitudinal direction with very slender silken 
cords. But the mode of its construction is even more 
remarkable than the substance of which it is fabricated. 
The caterpillar's first process is to form its slips of bark 
into two fiat triangular wing-like pieces, projecting oppo- 
site to each other from each side of the twig, somewhat 
like the feathers of an arrow. It does not, perhaps, re- 
quire any great degree of intelligence in a larva to give 
its cocoon the usual oval form, when it begins to arrange 
its materials in that shape from the very first, and round 
so good a mould as its own bent body; but we surely must 
admit that it is a task to which no stupid artist would be 
competent, to form first a multitude of strap-shaped la- 
minae into two triangular plates, and then to bend these 
plates into a case resembling the longitudinal section of a 
cone, with an elliptical and protuberant base, — the figure 
which the cocoon of this insect assumes. All the minu- 
tiae of the manoeuvres which it employs in this nice ope- 
ration could not be comprehended without a more diffuse 
explanation than I have here room to give : suffice it to 
say, that the caterpillar fastens silken lines to each exterior 
opposite and longer side of the laminae, and by applying 
all the weight of its body forces them to bend and ap- 
proach each other, in which position it secures them by 
other shorter lines. It next repeats the same process 
with the upper and shorter sides of the plates ; which 
when joined form the base of the cocoon. Both these 
tasks are accomplished in less than an hour, and the seams 
are so nicely joined as to be imperceptible. A fine inner 
tapestry of silk, covering all the asperities of the exterior 



232 STATES OF INSECTS. 

walls, concludes its labours a . It is to be lamented that 
Reaumur was unacquainted with the moth that proceeds 
from the pupae inclosed in these ingenious cocoons ; 
which being small, and precisely of the same colour as 
the bark of the twig that supports them, are not to be 
discovered but by a very narrow inspection. It would 
seem, however, to be Noctua Singula of Berkhausen, 
Pyralis strigulalis of Hubner b . The larva, he informs 
us, is found in May : its body is flatter than common, of 
a yellowish flesh-colour, clothed with tufts of red hair on 
each segment, and furnished with fourteen feet. Should 
this description enable you to detect it upon your oaks, 
a view of its ingenious procedures would amply repay 
you for the trouble of seeking for it. The larvae of Ce- 
ntra vi?iula, Stauropus Fagi, and several other moths, 
form their cocoons of grains of wood gnawed from the 
trees on which they feed. These grains they masticate, 
mixed with a glutinous fluid secreted from the mouth, 
into a paste, which forms a covering of an uniform smooth 
texture, and so hard as not readily to yield to a knife. 
Of a substance apparently nearly similar is composed 
the cocoon of a weevil related to Liparus Pini • which 
with its inhabitant was given me by the ingenious Mr. 
Bullock. A little moth, whose ravages have been before 
noticed c , lines the interior of the grain of barley, of 
which it has devoured the contents, with silk ; divides it 
into two apartments, into one of which it pushes the ex- 
crement ithad voided, and in theother assumes thepupa d . 
These, and the other larvae mentioned above, com- 

a Reaura. i. 54,5—. b j> ljra i s.3. L iii./. 16. 

c See above. Vol. [.p. 1/2 . 

d Reaum. ii. 491. 



STATES OF INSECTS. 233 

monly form their cocoons of the substances I have indi- 
cated ; but when by any cause they are prevented from 
access to them, they often substitute such other materials 
as are at hand. Reaumur fed a larva that formed its 
cocoon of minute fragments of paper, which with its 
mandibles it had cut from the piece that covered the glass 
vessel that contained it a : and the same circumstance 
happened to Bonnet. 

Upon a former occasion I described to you the cases 
of various kinds formed and inhabited by the insects of 
the Trichoptera Order {Phryganea L.) commonly called 
case-worms b . As these serve for the pupa as well as 
the larva, they may be regarded as a kind of cocoon. I 
shall not repeat here what I then said ; but having pur- 
chased from the collection of the late Mr. Francillon 
some that seem to belong to this or some cognate tribe, 
that are of a curious construction, I shall give you some 
account of two or three of them in this place. The first 
is not quite thi-ee inches long, of a sublanceolate shape, 
but rather widest towards one end. It consists of an in- 
ternal tough and thick bag or cocoon, of a silk resem- 
bling fine wool of a dirty white colour, which is closely 
covered transversely by pieces of the stalk of a plant, 
about three-fourths of an inch in length, and crossing 
each other at an obtuse angle. The next is thicker and 
shorter: the internal bag is just covered with small frag- 
ments of wood like sawdust ; over these are fastened ir- 
regularly, short stout pieces of a pithy stick or stalk, and 
the whole is clothed with a very close-woven ash-co- 
loured web. It seems difficult to conceive how the in- 
closed animal could contrive to cover her habitation with 
a Reaum. i. 540. b See above, Vol. I. 167—. II. 264. 



23i STATES OF INSECTS. 

this web without going wholly out of it. The third is 
the most curious and remarkable of all. It is nearly six 
inches long, and about four-fifths of an inch in diameter. 
It consists of a bag of thick cinereous silk web, to which 
are fastened, in a sextuple series, pieces of stick about an 
inch long, the end of one mostly resting upon the base of 
another: between each series a space of about three-tenths 
of an inch intervenes, but at the apex they all converge. 
This probably imitates the branch or stem of some tree 
or plant, in which the leaves are linear, and diverge but 
little from the stem. A label upon it states its country to 
be New Holland. I suspect the inhabitants of the two 
last cocoons to be terrestrial animals : the first is proba- 
bly a true aquatic case-worm. 

The same purpose for which the cocoons above de- 
scribed serve, is answered in the case of numerous Di- 
pterous insects, by a humble and less artificial contriv- 
ance — the skin, namely, of the larva ; which, as was be- 
fore observed a , is never cast, but, when the insect is about 
to enter into the pupa state, assumes a different form and 
colour; becomes of a thicker and more rigid texture; 
and defends the included pupa, which is separate from it, 
till its exclusion. In this case the mouth of the larva is 
constantly different from that of the perfect insect, or at 
least has not with it those relations as to number and 
kind of organs, which have been observed in the mouth 
of other larvae compared with the insects that they pro- 
duce. The animal, immediately after it is clothed with 
this skin, if it is opened, exhibits only a soft gelatinous 

a See above. Vol. I. p. 67. 



STATES OF INSECTS. 235 

pulp, in the surface of which the exterior organs of the 
adult insect cannot yet be detected. Nature requires 
more time for their elaboration, or at least for the ap- 
pearance of their outline, and to consolidate them. This 
pulp first takes an oblong form {Boule allongee Reaum.), 
and afterwards that of the insect it is destined to give 
birth to a . The skin of the larva also serves for a cocoon 
to the pupa? of male Cocci b . The grub of the genus An- 
threnus, so destructive to our cabinets of natural objects c , 
when it assumes the pupa does not quit its skin, but only 
splits it open longitudinally on the back, and when it 
becomes an imago makes its exit through the orifice d . 
Some Lepidopterous larva? even (Alucita pentadactyla, 
Callimorplia rosea, &c.) assume the pupa state within 
their last skin e . 

When a larva has finished its cocoon, — which with 

1 N. Diet. d'Hist. Nat. xvi. 269—. xxii. 76. 

b Reaum. iv. 32. The author here quoted asserts that the grub of 
Ichneumon Larvarum L. retains its skin, which, he says, is so trans- 
parent that the form of the nymph can be seen through it. Ibid. ii. 
447. De Geer, however, found that this really did cast its skin, 
which is so transparent as to be scarcely visible, by pushing it gradu- 
ally towards the anus, where it soon dries up and cannot then be dis- 
covered. De Geer ii. 893 — . According to Rdsel the same circum- 
stance attends the transformation of Coccinella renipustulata Illig. 
(C. Cacti Ent. Brit.), which at first perplexed him not a little. It is 
probable that in this case the retention of the skin was accidental ; 
for some of the grubs of a Mycetophila, the transformation of which 
I observed, became pupae within their last skin, while others wholly 
disengaged themselves from it. The cause of this variation, I con- 
jectured, arose from the former being too weak to extricate them- 
selves from the skin. 

c See above, Vol. I. p. 238. Byrrhus Musceorum belongs to this 
genus. 

d N. Did. a" Hist. Nat. ii. 161. e Pezold. 102. 



236 STATES OF INSECTS. 

some species, that proceed so earnestly as though they 
had not a moment to lose, is the work of a few hours, of 
others about two or three days, — after a certain interval 
it casts its last skin, which is usually suffered to remain 
in the cocoon (but which one moth, Geometra lacertinaria, 
ejects through an opening purposely left in its bottom), 
and the pupa makes its appearance a . This interval is 
exceedingly various. Most larvae assume the pupa state 
within a few days after they have formed their cocoons ; 
but some not for several weeks, or even months. The 
caterpillar of Bombyx cceruleocephala, according to Rosel, 
lies three weeks in the cocoon before this change is ef- 
fected ; those of many Pujrivora and Diploleparioe Latr., 
according to Reaumur, six months b ; that of Phalcena 
urticata nine months c ; and that of Cimbex lutea, accord- 
ing to De Geer, sometimes eighteen months d . Brahm 
observes, that such larvae of the double-brooded moth, 
Hepialus Testudo, as form their cocoons in autumn, do 
not become pupae until the following spring ; while those 
which form them in summer undergo this change in a 
few days e . From this fact it might be conjectured, that 
the degree of heat prevailing at the time the insect in- 
closes itself determines the period of the pupa's appear- 
ance ; but this supposition seems contradicted by what 
Reaumur observed of a brood of the larvae of Phalcena 
urticata^ just mentioned, which, though they formed 
themselves cocoons in September, did not become pupae 
till the June following f . I am unable, therefore, to as- 
sign any plausible cause for these extraordinary varia- 

a De Geer i. 339—. t Reaum. ii. 423, and iii. 497. 

c Ibid. i. 605. 'i De Geer ii. 941. 

e Brahm Insek. 72. f Reaum. ubi supra. 



STATES OF INSECTS. 237 

tions. The difficulty of comprehending how animals be- 
fore so voracious can live so long without food may be 
partly surmounted, by adverting to the circumstance of 
its having attained its full growth, and laid up a store of 
nutriment for the development of the perfect insect. It 
is consequently no more wonderful that it should not 
have need of any further supply without casting off its 
upper integument, than that it should not eat after hav- 
ing done so and become a pupa. 



LETTER XXXI. 



STATES OF INSECTS. 

PUPA STATE. 

W E have now traced our little animals through their 
egg and larva states, and have arrived at the third stage 
of their existence, the Pupa State. This, to include all, 
can only be defined, — that state intervening between the 
larva and imago, in which the parts and organs of the 
perfect insect, particularly those of sex, though in few 
cases fully developed, are prepared and fitted for their 
final and complete development in the last-mentioned 
state ; and in which the majority of these animals are 
incapable of locomotion, or of taking food. 

Pupae, like larvae, may be separated into two great di- 
visions : — 

I. Those which, in general form, more or less resem- 
ble the larvae from which they have proceeded. 
II. Those which are wholly unlike the larvae from 
which they have proceeded. 

I. To the first division belong, with some exceptions a , 

a In the Hemiptera the male Cocci (Reaum. iv. 32.) and Aleyrodes 
(Ibid. ii. 311.) belong to the second division. 



STATES OF INSECTS. 239 

the Dermapt era, Orthoptera, Hemiptera, and most Aptera, 
with the neuropterous tribes of Libellulina, Epkemeriria, 
and the genus Termes, in the class Insecta,- and the majo- 
rity of the Arachnida. This, like the first division of 
larvae, may be subdivided into two corresponding smaller 
sections ; the first including those pupa? which resemble 
the larvae, except in the relative proportion and number 
of some of their parts ; and the second those that resem- 
,ble them, except in having the rudiments of wings, or of 
wings and elytra. 

i. The first subdivision will include the pupae, if they 
may be so called a , of insects of the Aptera order, and of 
the class Arachnida : as, lice, Podurce, Lepismidae, centi- 
pedes, millipedes, mites, harvest-men, spiders, scorpions, 
&c. These mostly differ from their larvae only in that 
the relative length or number of their legs, the number of 
the segments of the body in some, or the development of 
their palpi, more nearly approach the characters of the 
perfect insect ; and in that while in their larva state they 
have two or more skins to cast, previously to their assump- 
tion of the imago, in their pupa state they have but one. 
In fact, this last circumstance is the only one which, 
strictly speaking, characterizes the pupae of this subdivi- 
sion ; as the changes which take place in the number and 
proportion of the organs are partly produced with each 
change of the larva's skin. And hence, as it is not easy 
to ascertain what number of skins a spider, for example, 
has yet to cast, and as both the larva and pupa differ so 
little from the perfect insect, it is very difficult to deter- 
mine in what state insects of this division are. From 

A The terms larva and pupa, applied to the insects of this subdivi- 
sion, are perhaps not strictly proper. 



240 STATES OF INSECTS. 

this difficulty has probably arisen the too great multipli- 
cation of species in some of these tribes, particularly the 
Arachnida, the larva and pupa having been mistaken for 
perfect insects. The pupae of this subdivision were 
named by Linne complete, from the near resemblance 
which they bear to the imago. 

ii. The second subdivision will include the pupae of 
the Dei'maptera, Qrthoptera and Hemiptera orders, with 
few exceptions ; as likewise the Libellulina, JEphemerina, 
and Termitina ? amongst the Neuroptera : including the 
well-known tribes of earwigs, cockroaches, crickets, 
grasshoppers, locusts, Ian thorn-flies, froghoppers (Ci- 
cada L.), bugs, plant-lice, dragon-flies, day-flies, white 
ants, &c. Of these, as in the former subdivision, the 
pupae are equally capable of eating and moving with the 
larvae, which they resemble, except in having the rudi- 
ments of wings, or of wings and elytra. The pupae of 
the three orders first enumerated differ from those of the 
Neuroptera in resembling the perfect insect in most in- 
stances, both as to shape and the organs for taking their 
food ; and in all other respects, except in not having their 
wings and elytra fully developed a . The resemblance of 
the pupae of the Libellulina and Ephemerina to the per- 
fect insects is more distant, and the above organs in the 
two states are very dissimilar ; for the pupae of the former 
are furnished with a prehensory mask similar to that of 
the larvae before described b , which the perfect insect has 

a The larvae and pupa? of many of the homopterous section of Hemi- 
ptera differ often from the imago, not only in their fore-legs (Plate 
XVI. Fig. 4.), but also in other respects. I have the larva of a Cen- 
trotus from Canada, given me by Dr. Bigsby, which has a long anal 
process or tail. b See above, p. 125— . 



STATES OF INSECTS. 241 

not; and those of the latter with the usual oral organs of 
masticating insects, of which the imago has scarcely the 
rudiments. 

I have applied the term rudiments to the wings and 
elytra in this state, not in a strict sense, but merely to 
denote their appearance ; for in fact the wings, &c. are 
complete, but only folded up longitudinally and trans- 
versely, and inclosed in membranous cases, which when 
the last change takes place remain attached to the pupa- 
rium or pupa-case. The tegmina or hemelytra in this 
state usually cover the wings, and the upper wings the 
under ; but in the Libellulina both are usually visible. 
Though commonly very small compared with the instru- 
ments of flight in the perfect insect, some of these rudi- 
ments, contrasted with the majority, are of considerable 
magnitude. This is the case with those of some species 
of Chermes, as we learn from De Geer a . 

II. The second grand division comprises by far the 
largest number of pupae : those of all coleopterous, strepsi- 
pterous, lepidopterous, hymenopterous, dipterous, and 
aphanipterous, and by far the majority of neuropterous in- 
sects, as well as the hemipterous genus Aleyrodes, and one 
sex of Coccus of the same order. These pupae, however, 
though agreeing in the circumstance of being unlike the 
larvae from which they proceed, differ from each other in 
several respects, and require to be divided into three 
great sections, as under: — 

i. Those pupae in which the parts of the future insect, 
being folded up under a membranous skin closely apply- 
ing to each, are distinctly visible. To this head belong 

a iii. 135, 
VOL, III. R 



'242 STATES OF INSECTS. 

generally, the pupae of coleopterous a and hymenopterous 
insects ; those of the neuropterous genera Myrmeleon and 
Hemervbius, &c. ; the Trickoptera ; amongst the Diptera, 
Culex, Tipula L., Tabanus, Bombylius, &c; and that of the 
flea (Pulex). These were the incomplete pupae of Linne. 

ii. Those pupae in which the parts of the future insect, 
being folded up under a harder skin, are less distinctly 
discoverable. To this subdivision belong the pupae of all 
Lepidoptera, and of them alone. These are what Linne 
termed obtected pupae. 

iii. Those pupae which are inclosed in the thick and 

opaque skin of the larva, through which no trace of the 

perfect insect can be discovered. These, which Linne 

termed coarctate pupae, include a large proportion of the 

dipterous genera; as CEstrus L., Musca L., Empis L., 

Conops L., &c. &c. b 

a The pupee of Cassida, Imatidium, &c. seem to vary somewhat from 
this type, the upper part being neither membranous nor exhibiting 
distinctly the form of the inclosed imago. 

b The following arrangement of pupae is perhaps in some respects 
better than that above given. But it is scarcely possible to propose 
one free from objections. 

I. Capable of eating and walking. 

i. Like the perfect insect, except in proportion and number 
of parts. 

1. Except in proportion (Lice, Podurce, Mites, Spiders, 

Scorpions, &c). 

2. Except in proportion and number (Centipedes, Mille- 

pedes'). 
ii. With rudiments of the organs of flight. 

1 . With oral organs resembling those of the perfect in- 

sect (Hemiptera). 

2. With oral organs differing from those of the perfect 

insect (Libellula L., Ephemera L.). 
II. Incapable of eating and walking, 
i. Incomplete pupae, 
ii. Obtected. 
iii. Coarctate. 



STATES OF INSECTS. 243 

I shall next advert, chiefly to the pupae of the grand 
division last described, under the distinct heads of sub- 
stance, figure, and par Is ,- colour, age, sex, motions, and 
extrication of the perfect insect, 

i. As to their substance — at first interiorly all pupae 
consist of a milky fluid, in which the unformed members 
of the future perfect insect may be said to float, and in 

Lamarck divides the pupee of insects that undergo a metamorphosis 
into three kinds, which he names — Chrysalis, Mumia, and Nympha. 

i. Chrysalis. Under this denomination he includes all inactive 
pupae inclosed in an opaque puparium which entirely conceals them. 
These he further subdivides into two kinds. 

1. Chrysalis signata. This term is synonymous with the Pupa 
obtecta of Linne, or the Chrysalis of Lepidoptera and some Diptera. 

2. Chrysalis dolioloides. Equivalent to the Pupa coarctata Linn, 
peculiar to those Diptera that assume* this state in the skin of the 
larva. 

ii. Mumia. All inactive pupae which are covered by a transparent 
skin, through which all the parts of the inclosed imago may be seen, 
subdivided also into two. 

1. Mumia coarctata. Corresponding with the Pupa incompleta 
Linn., which includes the Coleoptera and most of the Hymenoptera. 

2. Mumia pseudonympha, confined to the Pupa of Phryganea and 
some others. This might be named Pupa subincompleta. 

iii. Nympha. Under this denomination are included all insects 
that undergo only a partial metamorphosis, and are active in their 
pupa state, corresponding with the Pupa semicompleta Linn, and also 
subsemicompleta MacLeay. See Anim. sans Vertebr. iii. 285 — . 

M. Latreille has started an ingenious idea on this subject with re- 
gard to these kinds of metamorphosis, which comprehends both larva 
and pupa under a distinct denomination : as thus — 

1. Demilarve and Deminympih, synonymous with the Semicomplete 
Metamorphosis. 

2. Larve and Nymph, answering to Incomplete Metamorphosis. 
.3. Caterpillar and Chrysalis, answering to Obtected Metamorphosis. 

4. Fermi larve and Pupa, answering to Coarctate Metamorphosis. 
N. Did. d'llist. Nat. xvi. 272. 

R 2 



244 STATES OF INSECTS. 

which they may be discerned, and separated with the 
point of a pin a . In proportion as these acquire consist- 
ency, and are more and more developed by the absorp- 
tion of the surrounding fluid, they occupy its place, and 
fill up the cavity of the puparium. The rest of this fluid 
passes off by transpiration b . Reaumur is of opinion that 
it is from the epiploon, or corps graisseux, that this matter 
is prepared, which he regards as analogous to the white 
of an egg c . In coarctate pupae the included animal, or 
the pulp that contains its germes (in which the limbs and 
body at first are not discernible), fills at this period the 
whole skin-cocoon ; but in proportion as the above eva- 
poration takes place, and the consolidation of the body 
and parts proceeds, it shrinks at each end, so that when 
near assuming the imago, a considerable cavity appears 
both at the head and tail of the cocoon d . At this period 
of its existence, from the quantity of fluid included in the 
puparium, the animal weighs usually considerably more 
than it does when become a perfect insect e . 

The exterior integument or skin of pupae, which is usu- 
ally lined with a very thin white pellicle, is of different 
consistence in different orders. In the Coleoptera and 
Hymenoptera it is, with a few exceptions, of a soft and 
membranous texture; in the Lepidoptera (especially those 
that are not defended by cocoons), and Diptera, it is more 
rigid and harder, being either coriaceous or corneous. 
Lepidopterous pupae, however, are not excluded from 



a N. Diet. a" Hist. Nat. vii. 57. b De Geer ii. 105. 
e Reaum. ii. 428 — . 

d Swamm. Bibl. Nat. Engl. Tr. ii. 32. t. xli./. 2. Comp. Reaum. 
iv. t. xxv. f. 1. 
* Ibid.L 144, 



STATES Of JNSECTS. 245 

the last skin of the larvae with this hard covering. At 
the moment of this change the envelope is nearly as soft 
and membranous as in the order first mentioned. But 
they are besides covered with a viscous fluid, which ap- 
pears to ooze out, chiefly from under the wings, and 
which very soon drying, forms the exterior hard shell a . 
At first the antennae, wings, and legs, like those of Coleo- 
ptera and Hymenoplera, can be each separated from the 
body; and it is only after these parts have been glued to- 
gether by the fluid just mentioned, which takes place in 
less than twenty-four hours b , that they are immoveably 
attached to the body of the pupa, as we usually see them. 
In fact, the essential difference between incomplete and 
obtected pupae seems to be, that in the former the limbs 
and body are only covered each with a single membranous 
integument, whereas in the latter they are besides glued 
together by a substance which forms an additional and 
harder envelope. It is not easy to explain the alteration 
that takes place in the texture of the skin of such dipte- 
rous pupae as retain the skin of the larva. In the latter 
this is generally a transparent and very fine membrane : 
yet the very same integument becomes to the pupa an 
opaque and rigid case. 

The surface of the skin of the greater number of pupae 
is smooth, but in those of many Papilionidce it is rugose 
and warty : this you may see, particularly in that of Pa~ 
pilio Machaon. In many of the hawkmoths (Sphinx L.) 
it is covered with impressed puncta. In Attacus Io the 
upper side of the channels that separate the intermediate 
segments of the abdomen are curiously striated with trans- 

' Reaum, i. 355. h N. Diet. a" Hist. Nat. ubi sup. 59. 



246 STATES OF INSECTS. 

verse stride, formed of very minute granula, the lower side 
being transversely sulcared. In some few instances, as 
in Arctia Salic is, Laria pudibunda and Jascelina, the skin 
of the pupa is clothed with hair a : as is also that of He- 
speria Bixce, according to Madame Merian b . De Geer 
has described a little beetle under the name of Tenebrio 
lardarius (Lairidius Latr., Corticaria Marsh.), the pupa 
of which is beset with very fine hairs, terminating in 
a spherical or oval button c . 

ii. I shall include under the same head both the ^figure 
or shape, and parts of pupae, as the latter in most kinds 
are either the same or nearly the same as those of the 
larva, or merely incasing those of the imago, so as not to 
require that detailed notice that I judged necessary when 
treating of the parts of larvae. 

With regard to incomplete pupae, nothing further can 
be said of their extremely vaviousjigure, than that it has 
a general resemblance to that of the perfect insect. The 
head, trunk, abdomen, and their respective external or- 
gans, are alike visible in both; but in the pupae, the latter, 
instead of occupying their natural situation, are all closely 
folded under the breast and abdomen : or, as in the case 
of the long ovipositors of some Ichneumons, laid along the 
back. In a specimen of some coleopterous insect now 
before me, the following is the order of the arrangement 
of the parts:— The head is inflexed; the mandibulae are 
open ; between them are seen the labium and labial palpi; 
these appear to cover and conceal the maxillae, and the 
maxillary palpi extend on each side beyond them ; the 

a Plate XVI. Fig. 14. N. Diet. d'Hist. Nat. vii. 59. 

b Ins. Surinam., t. xliv. <■- De Geer v. 47. t. ii./. 29—31. 



STATES OF INSECTS. 247 

antennas pass above the thighs of the two anterior pair 
of legs, and then turning clown over the breast between 
them and the posterior legs, repose upon the base of the 
wings ; which also are turned down between the inter- 
mediate and posterior pair of legs, and rest upon the lat- 
ter; the tibiae are bent in and folded upon the thigh, 
and the tarsi turn outwards a . In another coleopterous 
species, the wings and elytra are placed under the hind- 
legs. In Hymenopterous pupae the antennae appear usu- 
ally to lie between the legs b . In many Tipulce the long 
legs are bent into three folds in the pupae ; but the tarsi 
are extended, and lie close to each other, the anterior 
pair being the shortest c . In a specimen belonging to 
this tribe in my cabinet, which I think contained Cteno- 
cera pectinicomis, the six leg-cases are of the same 
length, exactly parallel and adjacent, and being annu- 
lated wear the appearance of tracheae d . These parts 
have each their separate case, so that a pin may be intro- 
duced between them and the body : which cases, as well 
as the general envelope, are usually formed of a fine soft 
transparent membrane ; but sometimes, as in the lady- 
bird (Coccinella), the tortoise-beetle (Cassida), the crane- 
fly ( Tipida), &c. it is harder and more opaque, so that 
though it is usually easy for a practised Entomologist 
from an examination of the pupa, particularly in the Hy- 
?nenoptera, to predict to what genus the insect to be dis- 

a In the pupa of Hydrophilus piceas (Lesser L. i. ii./. 13, 14), the 
arrangement of the parts is nearly the same, but the tarsi are not re- 
flexed. 

b Ibid.f. 9, 10. De Geer ii. i.xxxii./. 5. Reaum. v. t. xxxvi./. 14. 

c Reaum. Ibid. t. ii./. 9. 

d The legs of Tipida replicala L. are placed in a similar way. De 
Geer vi. t. xx./. 1 2. I. 



c 2iS STATES OF INSECTS. 

closed from them will belong, yet in these cases the organs 
being not so conspicuous, a less experienced examiner 
might be perplexed, and unable to come to a conclusion. 
Although hymenopterous pupae have usually no parts 
but what are afterwards seen in the perfect insect, this is 
not the case with several coleopterous and dipterous ones, 
which are furnished with various temporary appendages, 
indispensable to them to bring about their final change, 
or for other purposes. Thus, the pupa of the male of 
Lucanus Cervus has two short, jointed anal processes a . 
That of Hydrophilus caraboides has a pedunculated lunu- 
late one; and moreover, the sides of the abdominal seg- 
ments, and the top of the thorax, are beset with hairs, 
which are not seen in the perfect insect 5 . The abdomen 
of many, also, is armed with spines. That, the arrange- 
ment of whose organs I lately described, has a quadruple 
series in the back of this part; viz. on each of the first five 
segments, 3, 2, 2, 3. The five first ventral segments also 
have on each side three spines; the inner are incurved, the 
intermediate nearly upright, and the outer one recurved. 
These spines, except those of the innermost ventral series, 
terminate in a bristle. In another coleopterous species the 
back part of the head is armed with a pair of lateral spines, 
and that of the thorax with three processes, the external 
ones armed with a single spine, and the intermediate one 
with a pair. De Geer has figured the pupa of an Asilus, 
the head of which is armed with eight spines — two ro- 
bust ones in front, and three smaller ones, connected at 
the base on each side. The abdominal segments, also, 
are fringed with spines c . The abdomen of the pupa of 

a Ros. t. 81 . " Ibid. t. 95. = De Geer vi. 237. t. xiv./. 8. 



STATES OF INSECTS. 249 

Ctenocera pectinicornis is armed with several strong co- 
nical spines, pointing mostly towards the tail, which is 
likewise the case with that of Tipula lunata a . As the 
above pupae are usually subterranean or subcortical, the 
spines assist in pushing them out of the ground, &c. 
The respiratory horns that proceed from the thorax of 
the pupae of many of the aquatic gnats will be noticed 
in another place. Those of Corethra culiciformis and of 
some other aquatic gnat-like Diptera, have their anus 
furnished with a pair of oars, or natatory laminae, by 
which they rise to the surface b . 

The figure of obtected pupae, or chrysalises, is more 
uniform. They are commonly obtuse at the anterior ex- 
tremity, and gradually contracted to a point at the poste- 
rior, or tail. The outline usually inclines to a long oval 
or an ellipse ; but in some, as Attacus Io and Luna, the 
pupa is shorter and more spherical. In Geometra sam- 
bucaria it represents an elongated cone, and in Hepialus 
it is nearly cylindrical. In the butterfly tribe [Papilio L.) 
the outline is frequently rendered angular by various pro- 
tuberances. 

In all these pupae may be distinguished the following 
parts :— ^first, the Head-case (Cephalo-theca), or anterior 
extremity; secondly, the Trunk-case [Cyto-theca), or inter- 
mediate part; and thirdly, the Abdomen-case [Gastro- 
theca). 

1. The Head-case covers and protects the head of the 
inclosed imago. From its sides behind proceed the an- 

a Reaum. v. i. ii./. 7- The anal and ventral spines of Tipula re- 
■plicata are also remarkable. De Geer vi. t. xx./. 14. 

b De Geer Ibid. 377. t. xxiii,/. 8, 9. n. Reaum. v. 42. t, vi./. 9. m n. 



250 STATES OF INSECTS. 

tennse-cases (Cera-theca); and before from the middle, 
the tongue-case ( Glosso-theca). Just below the base of the 
antennae-case you may discern the eye-cases (Ophthalmo- 
theca), surrounded on their inner side by a crescent- 
shaped laevigated piece, which may perhaps transmit 
some light to the inclosed prisoner. 

2. The Trunk-case, divided into the thorax, or upper 
surface, extending from the head to the dorsal segments of 
the abdomen, and consisting of three pieces, answering to 
the prothorax, mesothorax, and metathorax of the perfect 
insect : the first answering to the prothorax small, the 
second covering the mesothorax very large, and the two 
next representing the metathorax, at first appearing to 
belong to the abdomen, but having no spiracle ; and the 
breast (pectus) or under-surface reaching from the head 
to the ventral abdominal segments, from which proceed 
the wing-cases (Ptero-theca) and leg-cases (Podo-theca), 
which organs, with the antenna-cases and tongue-case, 
entirely cover, or rather form, the breast. The arrange- 
ment of the whole is as follows : — The wing-cases, which 
are more or less triangular, and exhibit the larger ner- 
vines of the wings, are a lateral continuation of the me- 
sothorax, which turn downwards from the sides of the 
breast, and cover, or replace, the three first ventral seg- 
ments of the abdomen. The antenna-cases, united to the 
anterior portion of the head just behind the eye-cases, 
repose immediately next to those of the wings running 
parallel with their inner margin. Then follow the legs, 
the tibiae forming an angle with the thigh, and the case 
of the anterior pair being innermost, and representing the 
breast-bone in the pupa. The tongue lies over the fore- 



STATES OF INSECTS. 251 

legs, except in the case of some sphinxes, which I shall 
notice afterwards : so that the eiosso-theca covers both 
them and it. 

3. The abdomen-case consists of ten segments when 
viewed on the back, and of only six when viewed below ; 
so that it might be said to have ten dorsal and six ven- 
tral segments : but the fact is, that the place of the three 
anterior ventral segments, or rather ventral portions of 
the segments, (for they form complete rings without any 
lateral suture, ) are replaced by the wings and other or- 
gans : in consequence of this, the fourth segment, which 
is less covered than the three first, at its posterior margin 
forms an annulus or ring. In counting the abdominal 
segments of a pupa, you must be careful not to include 
the piece that represents the metathorajc, which looks as 
if it belonged to the abdomen a . In the pupae of butter- 
flies you will discover evident traces of ten dorsal seg- 
ments ; but in many moths, and some hawk-moths, you 
will perceive at first only eight, or even seven, but a closer 
examination will enable you to discover the line that 
marks out the others ; and if you divide the puparium 
longitudinally, and inspect its internal surface, you will 
see very visible sutures between them. The intermediate 
segments are sometimes separated from each other and 
the preceding and subsequent ones by deep channels. 
In the pupa of Papilio Machaon there is one such chan- 
nel between the third and fourth segments. In Bombyx 



a The caterpillar consists of twelve segments (Lyonnet t. i.f. 4,5), 
excluding the head ; on each of which, except the 2d, 3d, and 12th, 
there is a pair of spiracles. The chrysalis usually exhibits an analogy 
to this structure, though the first, second, and last pair of spiracles 
are more or les3 obsolete in most. 



252 STATES OF INSECTS. 

regalis the channel is between the sixth and seventh, and 
in B. imperatoria there are three, namely, a channel be- 
tween the third and fourth, and fourth and fifth, and fifth 
and sixth segments. The way in which insects with an 
exserted sting fold it in the pupa seems not to have been 
noticed ; but from an observation of De Geer upon one 
species of Ichneumon, it appears to be turned up over the 
back of the abdomen a . 

These little animals, thus swathed and banded, exhibit 
no unapt representation of an Egyptian mummy ; though 
Lamarck applies the term Mumia to incomplete pupae b , 
to which it seems less happily applicable. 

Chrysalises, as to the modifications of their general 
figure, maybe conveniently divided into two great classes : 
Jirst, those that have no angular projections, the anal 
mucroof some excepted, on different parts of their body; 
and secondly, those which have such projections. Each 
of these classes affords variations in its peculiar charac- 
ters which require to be noticed. 

1 . The first of these are called angular pupae c , and 
are confined to the Butterfly or diurnal tribes. In some 
the head projects into one short conical protuberance : 
this you may see in the chrysalis of the common cabbage 
butterfly (Pieris Brassicce), and others of the same ge- 
nus d ; in the brimstone-butterfly (Colias Rhamni% and 
in the beautiful purple emperor or high-flier ( Apatura 
Iris F. f ): though in this last it is not conspicuous. But 

a De Geer ii. 847. t. xxix./. 7. a b. 
b Animaux sans Vertebres, iii. 287. 
r N. Diet, a" Hist. Nat. vii. 57. 
d Sepp ii. t. If. 4. t. ii./. 4. t. iv. f. 5. 
" Plate XVI. Fig. 12. 
f Plate XVI, Fig. 10, 



STATES OF INSECTS. 253 

the most remarkable instance of a single eminence from 
the head is exhibited by the pupa of a tropical butterfly 
(Morpho Idomeneus Latr.), figured by Madame Merian. 
In this the head projects into a long incurved obtuse 
horn a . In others the head is armed with two mucros, 
or conical eminences. This is the case with the common 
butterfly of the nettle ( Vanessa Urticce F. b ), and with that 
of the beautiful Papilio Machaon c . In these the promi- 
nences are trigonal. These processes, which in some, as 
in the peacock-butterfly ( Vanessa Io), stand upright d , 
and in others diverge (Papilio Machaon), form the eye- 
cases of the included imago; and in their outer base 
is planted the crescent-shaped piece I lately mentioned, 
which seems intended to convey light into it. In many 
the prothorax, besides a lateral angular projection, has 
in the middle another triangular or trigonal one, some- 
what resembling a Roman nose ; on each side of which 
is a smaller elevated black point : so that it requires no 
great stretch of imagination to find out in it a sort of re- 
semblance to the human face, which, though not quite 
so striking as honest Goedart figures it e , is however very 
considerable. In the pupa of Morpho Menelaus, figured 
by Madame Merian f , this nasiform prominence of the 
prothorax is extended into a long arched horn, reaching 
to the middle of the abdomen. The pupa of the silver- 
washed fritillary (Argynnis Paphia F.), and others of the 
same genus, exhibit beneath this nasiform prominence 



a Ins. Surinam, t. Ix. It is singular that the chrysalis of its congener, 
Morpho Teucer, which she figures t. xxiii., exhibits no such process. 
The larvEe also widely differ. b Plate XVI. Fig. 11. 

c Sepp ii. t. hi./. 5. d Sepp i. t. viL/. 5. 

e De Insectis, ed. Lister. t.\. { Ins. Surinam, t. liii. 



2\54 STATES OF INSECTS. 

a very deep depression, itself beset with one or more se- 
ries of smaller angular elevations. The back of the ab- 
domen is often furnished with two rows of protuberances, 
in some species larger, in others smaller a ; sometimes 
sharp and conical, and sometimes flat, and in some in- 
stances resembling the fins of fishes 5 . These bosses 
usually decrease in size towards the tail. 

2. The second kind of chrysalises are denominated 
conical c . These, which include the crepuscular and noc- 
turnal Lepidoptera, and the butterflies with onisciform 
larvae, have no protuberances, and are less variable in 
their form — their anterior extremity being almost con- 
stantly oval and rounded, and their posterior conical and 
acute. An exception to this form is met with in the pupa 
of a moth long celebrated (Lasiocampa Pithyocampa) d i 
which has the head acute and the tail obtuse, and armed 
with two points e . Another occurs in that of the Cossus, 
which has two points on the head, by which it makes 
an opening in its cocoon : when it assumes the imago, 
one of these is placed below the other f . And some 
few have the anterior end nearly flat instead of rounded. 
The pupa of the orange-tip butterfly (Pieris Cardamines) 
seems intermediate between the angular and conical 
kinds: it is somewhat boat-shaped, and distinguished 
by a fusiform process from the head and tail ». Other 
modifications of the usual figure are met with, but are 
for the most part so slight as not to require notice. One 

a Sepp i. t. ii,/. 6. t> N. Diet. d'Hist. Nat. vii. 60. 

c Ibid. 57. d See above, Vol. I. p. 131. 

e Reaura. ii. 158. t. viii./. 4,5. 
f Lesser L. i. 160. note. t. ii./. 19. 

g N. Diet. d'Hist. Nat. xxvi. 165. Reaum. i. 347. Rosel says this 
is present only in some individuals. I. ii. 47. 



STATES OF INSECTS. 255 

or two, however, should not be passed over. The pupse 
of many hawk-moths (Sphinx L.) have the anterior piece 
of the head-case elongated into a sort of cylindrical pro- 
boscis, which is incurved beneath the breast : you will 
find this formation in S. Convolvuli and Ligustri a . In 
some, as in a species figured by Madame Merian, that 
feeds upon the Annona squamosa^ it is rolled up like a 
serpent in many folds b . In Noctua Linarice the tongue- 
case turns upwards, and is prominent laterally beyond 
the body c . This singular appendage is one of those 
beautiful instances of compensating contrivances, as Dr. 
Paley calls them, which perpetually occur in the insect 
tribes. The tongue of these hawk-moths is of very great 
length, often three inches, while the pupa itself is scarcely 
two ; it could not possibly, therefore, have been extended 
at length, as it is in common cases, but is coiled up 
within the above protuberance. When the tongue is but 
a little longer than the breast, the ordinary plan is ad- 
hered to, but the apex of the breast projects a little over 
the abdomen into a sort of nose, in which the end of the 
tongue is contained. This conformation may be seen in 
the pupa of Noctua Gam?na, Verbasci, and many other 
species. Sometimes, as in N. Linaria F., this projection 
is recurved into a short horn. 

I have before adverted to the adminicula or short spines 
looking towards the anus, with which the dorsal segments 
of the abdomen of some pupas are armed ; and by which, 
when the time for their exclusion is arrived, they are 
enabled to push themselves upwards or outwards from 

a Plate XVI. Fig. 13. a. b Ins. Surinam, t. iii. 

c De Geer ii. 433. t. vlii./. 4. t. 



256 STATES OF INSECTS. 

their several places of confinement a : you will find these 
in the pupa of the great goat-moth (Cossus ligniperda) ; 
and in the cylindrical pupa of the moth called the ghost 
(Hepialus Humuli F.) there are two rows of sharp trian- 
gular spines on the back of each segment. These are not 
laid flat, but, as they do also in the Cosstis, form an acute 
angle with the body ; which gives them greater power of 
resistance. Those that constitute the row nearest the 
base of the segment are longer than the anterior row, 
the middle spines than the lateral ones. The first and 
last segment are without them, and the last segment but 
one has a sharp ventral transverse ridge, armed with 
many sharp teeth b . The abdominal spines lately men- 
tioned, of semicomplete pupae, are also adminicula. 

The tail of this description of pupae is in many in- 
stances armed with a mucro, or sharp point, emerging 
from its upper side. You will see this in most hawk- 
moths. In the pupa of Hesperia Proteus the mucro is 
truncate at the apex ; in that of Bombyx imperatoria it is 
long, and terminates in two diverging points. In the 
majority of chrysalises of both descriptions the tail is 
acute, and usually furnished with hooks of different kinds. 
These are so various in shape and number, &c. that they 
would probably afford good characters for discriminating 
many allied species. In some there are but two or three, 
in others five or six, in others they are more numerous c . 
Sometimes they are quite straight d , but most commonly 
recurved, so as to form a hook. The hawk-moths, and a 

a See above, Vol. II. p. 300. 

b This description was taken from ajmpariam in my own cabinet ; 
it is similarly described by De Geer i. 490. t. vii./. 2. 

c Plate XXIII. Fig. S, 9. a Kliemann Beitrage, 304. 



STATES OF INSECTS. 257 

lew others, as Bombi/x Pihi, Centra Vinida, &c, have no 
anal hooks whatever. Under this head I shall observe, 
that in many conical pupae below the anal angle or rau- 
cro, is the appearance of a vertical foramen or passage : 
this is particularly conspicuous in Hcpialus, in which it 
is surmounted by a bifid ridge, and has under it a pair of 
minute black tubercles. 

A pretty accurate judgement of the division to which 
the perfect insect when disclosed will belong, may usually 
be formed from the figure of its chrysalis. All the angu- 
lar ones, with scarcely any exception, inclose butterflies. 
The converse, however, does not hold ; for some that are 
not angular, as those of Parnassius Apollo and Mne- 
mosyne, and most of the Linnean Plebeii urbicola, also 
inclose flies of that description. With these exceptions, 
all conical chrysalises give birth to moths or ha'wkmot/is. 
An idea even of the family or genus under which the 
perfect insect will arrange, may be generally formed from 
.the figure of the chrysalis ; less distinctly, however, in 
the conical or rounded, than in the angular kinds, in 
which the prominences of the head and trunk, as before 
explained, usually vary in different families. Even the 
sex of some moths may be judged from the pupae : those 
of females being thicker; and those also of the females that 
have no wings, or only the rudiments of them, will of 
course vary somewhat from the ordinary form : but there 
is a still more striking difference in that of Callimorpha ? 
vcstita F., and others of the singular tribe before no- 
ticed*, called by the Germans Sacktrager (sack-bearers), 
from the sack-like cases in which the larva resides. The 

5 See above, Vol. I„ 464. 
VOL. ill. s 



258 STATES or INSECTS. 

females of these having not only no wings, but no anten- 
nae, and legs not longer than those of the larva, their 
pupa more resembles that of a dipterous than of a lepi- 
dopterous insect, it being not easy to determine which is 
the head and which the tail a . 

In these too we can often learn from the outline of the 
wing-cases, whether the inhabitant of the chrysalis has 
these organs indented or intire. If the former, the mar- 
gins of these cases are sinuate, as in that of Vanessa 
C. album ; if the latter, they are intire, as in Piey^is Bras- 
sicce. Even in conical pupse, — the size, the shape of the 
antennae, which may be distinguished through the skin 
that covers them, and slight modifications of the ordi- 
nary form, — give indications of the genus of the included 
insect sufficiently conclusive to a practised eye. 

The true figure of coarctate pupae when they are ma- 
ture, the parts of the future fly being very visible, and 
each being included in a separate case b , is that of those 
that belong to the incomplete division ; but as this is a 
character not cognizable without dissection, it is customary, 
in speaking of pupae of this description, to refer solely to 
the shape of the exterior covering, which is in fact a cocoon 
formed of the dried skin of the larva moulded into a dif- 
ferent form. In this sense the figure of coarctate pupae is 
extremely various. The majority of them are more or less 
oval or elliptical, without any distinct parts, were it not 
that they usually retain traces of the segments which com- 
posed the larva's body c . Of this figure are the pupae of the 
common cheese-maggot d , and many other flies. Others 

a Von Scheven in Naturf stk. xx. 64. t. ii./. 4. 

b Plate XVII. Fig. 2. Lesser L. t. ii. /. 26. 

c Plate XVII. Fig. 1. Lesser L. /. ii./. 24, 25. 

d Whether M. Meigen has separated this fly generically from 



STATES OF INSECTS. 259 

(Sepedon Latr.) have the pupa shaped like a boat. That 
of Sccevcl Pyrastri F. assumes the figure of a flask ; or, 
according to Reaumur's more accurate comparison, of a 
tear a . The tail of many of these pupae, particularly of 
aquatic species, is elongated into a sort of beak, either 
simple or forked, or is beset with spines variously ar- 
ranged. The pupa of Stratyomis Chamceleon, and other 
allied species, differs from all the rest of this subdivision 
in retaining the exact form of the larva b ; and hence con- 
stitutes an exception to the general character of our se- 
cond great Division. 

iii. There is much less variety in the colour of pupae 
than in that of larvae. The majority of coleopterous and 
hymenopterous pupae are white, or whitish ; of lepido- 
pterous and dipterous, brown of various shades, often 
verging on black in the former and on red in the latter. 
The angular lepidopterous ones, however, are more 
gaily decorated. Some, Pieris Brassicce, are of a greenish 
yellow, marked with spots of black; others are of a uni- 
form green, Apatura Iris, Pieris Cardamines ; others, red- 
dish, Vanessa C. album; others again red with black 
spots, Urania Leilus c . A still greater number shine as 
though gilded with burnished gold — either applied in 
partial streaks, Vanessa Cardui ; or covering the entire 
surface, Vanessa Urticce. It was from this gilded appear- 
ance in some obtected pupae that the terms Chrysalis and 

others, I am not aware : in my catalogue it stands under the name of 
Tyrophaga. 

a Reaum. iii. 376. t. xxxi./ 7- 

b Ibid. iv. 318. t. xxiii./. 1—4. xxv./. 1. 

e Ins. Surinam, t. xxix. 

S 2 



260 STATES OF INSECTS. 

Aurelia were applied to the whole. The alchemists mis- 
took this for real gold ; and referred to the case as an 
argument in favour of the transmutation of metals. But 
Reaumur has satisfactorily shown, that in this instance 
the old proverb is strictly applicable — " AH is not gold 
that glitters." He found that this appearance is owing 
to the shining white membrane immediately below the 
outer skin, which being of a transparent yellow gives a 
golden tinge to the former ; in the same way that tinfoil, 
when covered with a yellow varnish, assumes the metallic 
appearance which we see in gilt leather. He mentions, 
too, that for the production of this effect — it is essential 
that the inner membrane be moist: whence may be ex- 
plained the disappearance of the gilding as soon as the 
butterfly is ready to escape from the pupa. The shade 
of colour in these gilded chrysalises is various: some are 
of a rich yellow, like pure gold; others much paler; and 
some nearly as w T hite as silver. That of Hipparchia 
Cassia F. is red with silver spots a . 

Though by far the greater number of the chrysalises 

of moths are of an uniform chestnut, brown, or black, 

a few are of other colours ; as that of Geometra alhiaria. 
which is of a glaucous blue; of Noctua sponsa, lilac; and 
of Noctua pacta, of a lovely blue, caused by a kind of 
bloom, like that of a plum, spread upon a brown ground. 
A similar bloom is found on that of Parnassius Apollo, 
and on the anterior part of that of Platypterix cultaria 
and sicula ; in which last, Kliemann observed it to the 

a Ins. Surinam, t. xxxii. Lister imitated the gilding of Chrysalises 
by putting a small piece of a black gall in a strong decoction of net- 
tles : this produced a scum, which when left on cup-paper, he says, 
will exquisitely gild it.— Ray's Letters, 87. DO. 



STATES OF INSECTS. 261 

be renewed when rubbed off a . Many pupae have the 
sheaths of the wings of a different colour from that of the 
rest of the body ; a few are variegated with paler streaks 
or bands, as Clostera Anastomosis, which has two red 
longitudinal stripes down its dark-brown back; and that 
of the common gooseberry and currant moth, which may 
be found in every garden, has alternate rings of black 
and yellow 5 . 

A few pupae vary in their colour, as the painted lady- 
butterfly (Vanessa Car dui), some of which are light-brown 
with gray streaks and golden dots, others wholly of a 
golden yellow or brown, others of a light green c . 

Almost all at their first assumption of the pupa state 
have a different colour from that which they take a few 
days afterwards. This last they retain until the disclo- 
sure of the perfect insect ; except some that have trans- 
parent skins, which a few days previously to this period 
exhibit the colours of the included animal, 

iv. There is as great variety in the length of the age 
of Insects in their pupa as in their larva state. Some 
species continue in it only two or three days (Aleyrodes 
Chelidonii Latr., Tinea proletella L.); others, as many 
weeks, or moriths, or even years. Each, however, has in 
general a stated period, which in ordinary circumstances 
it neither much exceeds nor falls short of. The only- 
general rule that can be laid down is — that small pupae 
continue in that state a shorter time than those of larger 
bulk. Thus, amongst coleopterous genera, the more mi- 
nute species of Curculio L. ; amongst the Hymenojptera^ 

a Seitrage, 181. h Sepp. pt. ii. t. ii,/. 4. c Rosel. I. i. 61. ii. 5, 



262 STATES OF INSECTS. 

the Ichneumones minuti L. ; amongst the Lepidoptera, the 
subcutaneous tribes ; and the majority of the Diptera, — 
remain as pupa? only a few days or weeks : while the 
larger species in all these orders commonly exist in the 
same state several months — many even upwards of two 
years. There are, however, numerous exceptions to 
this rule ; for some large pupae are disclosed in a much 
shorter time than some others not a twentieth part of 
their bulk. 

The reasons both of the rule and of the exceptions to 
it are sufficiently obvious. And first, as to the rule : — 
If you open a pupa soon after its assumption of that state, 
you will find its interior filled with a milky fluid, in the 
midst of which the rudiments of its future limbs and or- 
gans, themselves almost as fluid, swim. Now the end to 
be accomplished during the pupa's existence is, the gra- 
dual evaporation of the watery parts of this fluid, and the 
development of the organs of the inclosed animal by the 
absorption and assimilation of the residuum. Reaumur, 
by inclosing a pupa in a stopped glass tube, collected a 
quantity of clear and apparently of pure water, equal to 
eight or ten large drops, which had evaporated from it, 
and was condensed against the sides of the tube, and it 
was found to have lost an eighteenth part of its weio-ht a . 
It is plain, therefore, that this necessary transpiration, 
other circumstances being alike, must take place sooner 
in a small than in a large pupa. Next, as to the excep- 
tions : — Since the more speedy or more tardy evaporation 
of fluids depends upon their exposure to a greater or less 
degree of heat, we might a priori conclude, that pupae 

a Reaum. i. 383. 



STATES OF INSECTS. 263 

exposed to a high temperature would sooner attain ma- 
turity, even though larger in bulk, than others exposed 
to a low one : — and this is the fact. The pupa of a large 
moth, which has assumed that state in the early part of 
summer, will often disclose the perfect insect in twelve or 
fourteen days ; while that of an Ichneumon, not one hun- 
dredth part of its size, that did not enter this state till 
late in autumn, will not appear as a fly for seven or eight 
months. But this is not the whole. The very same in- 
sect, according as it has become a pupa at an earlier or 
later period of the year, will at one time live but a few 
weeks, at another several months, in that state. Thus, 
if the caterpillar of Papilio Machaon, one of those which 
has annually a double brood, becomes a pupa in July, 
the butterfly will appear in thirteen days : if not until 
September, it will not make its appearance until the June 
following ; that is, not in less than nine or ten months : 
and the case is the same with the pupae of Noctna Psi, 
and of a vast number of other insects. To put beyond 
all doubt the dependence of these remarkable variations 
on temperature merely, it was only necessary that they 
should be effected, as Lister long ago advised a , by arti- 
ficial means. This Reaumur accomplished. In the 
month of January he placed the chrysalises of several 
moths and butterflies, which would not naturally have 
been disclosed until the following May, in a hothouse : 
the result was, that the perfect insects made their appear- 
ance in less than a fortnight, in the very depth of winter ; 
and by other numerous and varied experiments he ascer- 
tained, that in this heated atmosphere five or six days 

3 Lister's GoeJarh 122. 



261- STATES OT INSECTS. 

hastened their maturity more than as many weeks would 
have done in the open air. The disclosed insects were 
in every respect perfect, and the females, after pairing, 
laid their eggs, and then died, just as if they had not 
been thus prematurely forced into existence. The con- 
verse of this experiment equally succeeded:— by keeping 
pupae the whole summer in an icehouse, Reaumur caused 
them to produce the fly one full year later than their or- 
dinary period a . 

This extraordinary fact leads us to a very singular and 
unexpected conclusion — that we have the power of 
lengthening or shortening the life of many insects at 
pleasure ; that we can cause one individual to live more 
than twice as long as another of the same species, and 
vice versa. Had Paracelsus made this discovery, it would 
have led him to pursue his researches after the elixir of 
immortality with redoubled confidence, and would have 
supplied him with an argument for the possibility of pro- 
longing the life of man beyond its usual term, which his 
sceptical opponents would have found some difficulty in 
rebutting. Even the logical Reaumur seems inclined to 
infer from it, that this object of the alchemists was not so 
chimerical as we are wont to conclude b . He confesses, 
however, if it were to be attained only by the same pro- 
cess as effects the extension of an insect's life — by pro- 
longing its state of torpor and insensibility, — that few 
would choose to enjoy it on such conditions. The man 
of pleasure, blunted by excess of use to all modern sti- 
muli, might perhaps not object to a sleep of a hundred 
years, in the hope of finding something new under the 

* Reaum. ii. 10—-. *> Ibid. 24, 



states or INSECTS. 265 

sun when he waked ; and an ardent astronomer would 
probably commit himself with scientific joy to a repose as 
long and as sound as that of the seven sleepers, for the 
chance of viewing his predicted return of a comet, on 
stepping out of his cave : but ordinary mortals would 
consign themselves to the perils of so long a night with 
reluctance, apprehending a fate no better than what be- 
tel the magician, who ordered himself to be cut in small 
pieces and put in pickle, with the expectation of becom- 
ing young again a . 

The duration, then, of an insect's existence in the 
pupa state, depends upon its bulk, upon the temperature 
to which it is exposed, and upon a combination of these 
two circumstances. This experiment appears very sim- 
ple. We seem to ourselves to have accomplished what is 
so often undertaken in vain — to have found an entrance 
into the cabinet of Nature, and to have made ourselves 
masters of the contents of one of the pages of her sealed 
and secret book. We deceive, ourselves, however : this 
book, when it seems most legible, is often interlined with 
sympathetic inks, if I may so speak, which require tests 
unknown to us for their detection. If you lay up a con- 
siderable number of the pupae of a moth now called Erio- 
gaster lanestris, the larva of which is not uncommon in 
June on the black-thorn, selected precisely of the same 
size, and exposed to exactly the same temperature, the 
greater number of them will disclose the perfect insect 
in the February following ; some not till the February of 
the year ensuing, and the remainder not before the same 

* This is a legend of Virgil, of which an account is given in The 

Lay of the Last Minstrel, Note xv. 12mo ed. 1822, p. 257. 



266 STATES OF INSECTS. 

month in the third year a . Mr. Jones of Chelsea, a most 
acute lepidopterist, in one of his excursions captured a 
female of Arctia mendica, another moth, which laid a 
number of eggs, thirty-six of which produced caterpil- 
lars : all these fed, spun their cocoons, and went into the 
pupa state in the usual manner, but at the proper season 
only twelve produced the fly. As this was no uncommon 
circumstance, he concluded that the rest were dead : to 
his great astonishment, however, in the next season twelve 
more made their appearance ; and the following year the 
remainder burst into life, equally perfect with the fore- 
going b . In this extraordinary result, which also occa- 
sionally has been observed to take place in the emperor- 
moth (Saturnia pavonia), the privet-hawkmoth {Sphinx 
Ligustri), and that of the spurge (S. Euphorbia:) c , and 
other species, — it is clear that something besides mere size 
and temperature is concerned : for, these circumstances 
being precisely alike, one pupa arrives at maturity in six 
months, and another of the same brood requires between 
two and three years. We can guess, that the end which 
the All-wise Creator has in view, in causing this remark- 
able difference, is the prevention of all possibility of the 
destruction of the species. Eriogaster lanestris and Arc- 
tia mendica, &c, for instance, are doomed, for some rea- 

a Haworth Lcpidopt. Britann. i. 125, An instance is recorded in 
Scriba's Journal, in which a pupa was not disclosed until the fourth 
year. B.i. st. iii. 222. Pezold. 170. 

b Marsham in Linn. Trans, x. 402. 

c Meinecken found, that of several pupse of Saturnia pavonia, 
some kept all winter in a room heated daily by a stove, and others 
in a cold chamber, some of both parcels appeared in March (none 
earlier), and some of both had not appeared in July, though evidently 
healthy. Naturf. viii. 143. 



STATES OF INSECTS. 267 

son unknown to us a , to be disclosed from the pupa in 
the cold and stormy months of February and March, 
almost every day of which in certain years is so ungenial 
that few insects could then survive exposure, much less 
deposit their eggs and ensure the succession of a progeny. 
Now, were all these to make their appearance in the per- 
fect state in the same year, it might happen that the 
whole race in a particular district would be destroyed. 
But this possibility is effectually guarded against by the 
beautiful provision under consideration, it being very im- 
probable that three successive seasons should be through- 
out unfavourable ; and without such occurrence, it is clear 
that some of the race of this moth will be preserved. In 
the case of other moths, whose pupae though disclosed in 
the summer are governed by the same rule, the prevention 
of the extinction of the species, by any extraordinary in- 
crease in a particular year of their natural enemies, seems 
the object in view b . But though the intention be thus 
obvious, the means by which it is effected are impene- 
trably concealed. What physiologist would not be puz- 
zled with the eggs of a bird, of which one-third should 
require for their hatching to be sat upon only a fortnight, 
another third a month, and the remainder six weeks? Yet 
this would be an anomaly exactly analogous to that ob- 
served by Mr. Jones with respect to the pupae of A. men- 
dica. Reaumur found that when the skin of pupae was 
varnished, so as to prevent absorption, the appearance of 



a The exclusion of certain moths, &c. from the pupa is probably 
regulated by the time their eggs require to be hatched, and the ap- 
pearance of the leaves that constitute their appropriate food. 

b Mr. Marsham makes a similar observation in Linn. Trans., ubi 
snpr. 



£68 STATES OF INSECTS. 

the fly happened nearly two months later than in ordi- 
nary circumstances. Are we to conjecture that those ol 
the moth just mentioned, or of E. lanestris, that are lat- 
est matured, from a greater degree of viscidity in the 
fluid that forms them % have thicker and more imper- 
vious skins than those disclosed at an earlier period? 
Or are we to refer the difference to some unknown pe- 
culiarity of organization ? On any supposition, the fact 
remains equally wonderful ; and I know of none the illus- 
tration of which is more worthy of the patient investiga- 
tion of the physiologist. 

As the period of maturity of the perfect insect is thus 
in some cases not fixed even to years, and as in many 
it seems dependent upon such variable causes ; nothing 
appears more improbable than that it should ever be 
so strictly determined, that even the week in which the 
fly will leave its pupa-case can be pretty accurately pre- 
dicted. Such, however, is the fact with regard to the 
Ephemera so interestingly described by Reaumur, the 
myriads of which that issue from the banks of the Seine 
all appear in two or three days, somewhere between the 
10th and 18th of the month of August 5 in every year; 
at which time the fishermen regularly expect them. A 
like regularity attends the appearance of those described 
by Swammerdam, which every year, for three days about 
the feast of St. John, issue in clouds from the Rhine c — 
Not only is the week fixed, but in several instances even 

a See above, p. 245. 

b The appearance of them sometimes continues to near the end 
of the month : it began on the 19th, when Reaumur observed them, 
vi. 480. 488. 

c Bill. Nat. E. Transl. i. 103-—, 



STATES OF INSECTS. 269 

the hoar. The Ephemerae observed by Reaumur appear 
at no other time than between eight and ten o'clock in 
the evening ; and so unalterably is their exclusion fixed, 
that neither cold nor rain can retard it. Between these 
hours, in the evenings on which they appear, you may 
see them fill the air, but an hour before or after, you will 
in vain look for one a . So also the silkworm-moth and 
the hawkmoth of the evening primrose [Sphinx CEno- 
therce) constantly break forth from the pupa at sunrise : 
and the hawkmoth of the lime [Smerinthus Tilics) as cer- 
tainly at noon b . Schroeter states, that of sixteen speci- 
mens of the death's-head-hawkmoth [S. Atropos) which 
he bred, every one was disclosed between four and seven 
o'clock in the afternoon c . 

Before I conclude this head, I must observe, that after 
a caterpillar or gnat has spun its cocoon, it sometimes 
remains for a considerable period before it incloses itself 
in the pupa-case, and casts off the form of a larva. Thus 
the little parasite [Ichneumon glomeratus L.) that destroys 
the caterpillar of the common cabbage-butterfly, remains 
a larva in its cocoon for many months, but it becomes a 
perfect insect a few days after it has put on its pupa- 
rium d ; and the caterpillars of the great goat-moth ( Cos- 
sus ligniperda), if they spin their cocoon in the autumn, 
remain in it through the winter in the larva stale; 
whereas, if they inclose themselves in the month of June, 
they assume the pupa, so as to appear as flies in three or 
four weeks e . It is not therefore easy to state precisely 

a Reaum. vi. 486. b Brahm. 423. 421. 

c Naturf. xxi. 75. A Reaum. ii. 423. 

* De Geer ii. 370. It is not certain, however, that De Geer did 
not, in this instance, mistake the winter habitation of a larva for a 



270 STATES OF INSECTS. 

the ao-e of those pupae which are produced from larvae 
that spin cocoons. 

v. I have not much to say with regard to the sex of 
pupae. The male is probably to be distinguished from 
the female by being smaller ; but in the first great divi- 
sion of pupae, those which resemble the larvae, and are 
locomotive, the female in numerous cases may be known 
by the Ovipositor, or instrument for depositing her eggs 
in their proper station : and the male also has his anal 
instruments. Sometimes in this state the animal is so 
matured, as to be capable of continuing its kind. I have 
found the pupae both of a Gryllus L. and of a Cimex L. 
in coitu. 

vi. Though the pupae of the second great division are 
usually not locomotive, yet I must not omit some notice 
of their motions. As the legs of insects in this state are 
folded within a common or partial integument, of course 
none of the pupae now under consideration, with the ex- 
ception of those of the Trichoptera order, can walk : co- 
arctate ones are even incapable of the slightest motion, 
and exhibit no symptom whatever of animation. Some 
of those that are termed incomplete, however, and most 
chrysalises, have the power of communicating to their 
bodies a slight movement, extending more or less in dif- 
ferent species, which is effected by the abdominal seg- 
ments solely. The latter, during the first twelve hours 
of being pupae, when their skin is soft, frequently turn 

cocoon intended to shelter the future chrysalis; since Lyonnet in- 
forms us that they spin a habitation to pass the winter in. Traite 
Anatomique, &c. 9. 



STATES OF INSECTS. 271 

themselves, that the side on which they lie may not be 
flattened ; afterwards by far the majority merely wriggle 
or twist their abdomen when touched, or in any way in- 
commoded or disturbed. We learn from De Geer, that 
the pupa of the ghost-moth (Hepialus Humuli), the co- 
coon of which is more than twice the length of the chry- 
salis, moves in it from one end to the other a . Bonnet 
observed one of a moth (perhaps Lasiocampa Quercus), 
which alternately fixed itself at the top and bottom of its 
spacious and obliquely-fixed cocoon ; descending slowly, 
but ascending as quickly, and almost in the same manner, 
as a chimney-sweeper in a chimney b . The pupa of the 
weevil of the water-hemlock (Lixus paraplecticus) will 
move from one end of the interior of a branch to another 
by means of its adminicular aided by the motion of its 
abdominal segments c . But the most locomotive of pu- 
pae of the second division are those of gnats, and many 
Tipulidans, which pass this state in the water. These 
will move from the bottom to the surface, and back again, 
with great facility and velocity. I have before mentioned 
several other motions of pupae d , which I shall not repeat 
here, by which they extricate themselves from their seve- 
ral places of intermediate repose, before they leave the 
puparium : if the imago were to be disclosed in the in- 
terior of a tree, or in the earth, its wings would be ma- 
terially injured in forcing its way out. The object of 
several of the above motions may be to alarm insects that 
might attack these defenceless beings. The twirling mo- 
tion in particular, formerly noticed e , in some species, by 

a De Geer i. 490. t. vii./. 3, 4. b CEuv. ii. 1. 

c De Geer v. 2.29. d Vol. II. 300—. 

e Vol. II. 298—. 



272 STATES OF JNSECTS. 

causino- a rustling against the sides of the cocoon, makes 
a considerable noise — so singular in that of a red under- 
win«-moth (Noctua pacta), that Rosel tells us, (who by 
the by was more timid than becomes a philosopher,) that 
the first time he heard it, he had nearly thrown away the 
box that contained it, in his fright a . 

vii. We are next to consider The extrication of the per- 
fect insect from the puparinm, or pupa-case, and from the 
cocoon. The period when the pupa has attained matu- 
rity, and the inclosed insect is ready to burst the walls of 
its prison, may be often ascertained. Just at this time 
the colour frequently undergoes an alteration, the golden 
or silver tint of the gilded chrysalises vanishes ; and those 
which are transparent, usually permit the form and co- 
lours of the insect within and the motions of their li bs 
to be distinctly seen through them. In the Libellulina 
the eyes become more brilliant b . The mature pupae of 
the moth lately mentioned (Eriogaster lanestris) have a 
particular swell of the abdominal segments, not apparent 
in those that are to continue till another season, or 
longer . Those of the case-worms [Trichoptera) push 
off the grates from the cases which they have hitherto 
inhabited, and swim about d . Other signs and motions 
doubtless predict the approach of this great change in 
other species, which have not been recorded. 

The mode in which insects make their way out of the 
puparium differs in different orders. In obtected pupa?, 
the struggles of the included butterfly or moth first effect 
a longitudinal slit down the middle of the thorax, where 

a I.iv. 101. b Reaum.vi. 407. 

e Haworth Lepidopt, Britann. i. 127. d De Geer ii. HUG, 



STATES OF INSECTS. 273 

there is usually a suture for the purpose. The slit ra- 
pidly extends along the head, and down the parts which 
compose the breast, and the insect gradually withdraws 
itself from its case. It is not, however, from the outer 
skin merely that it has to disengage itself, but also from 
a series of inner membranous cases, which separately in- 
close the antennae, proboscis, feet, &c, as a glove does 
the fingers ; and similar cases inclose the parts of the 
perfect insect in pupas of all the other orders. This is 
sometimes a work of difficulty, but ordinarily it is effected 
with ease. 

Incomplete and semicomplete pupae undergo nearly the 
same process, save that in them the body is not swathed 
up in a common case ; and therefore they have only to 
liberate themselves from the partial cases that envelop the 
several parts of their body. 

In coarctate pupae, as those of Muscidtz, Syrphidce, 
(Estridze, &c, the process is different. Their outer-case 
is ordinarily more rigid and destitute of the sutures, 
which in the former tribes so easily yield to a slight effort. 
Yet in these, at the anterior end under which the head of 
the fly lies, and from which it always issues, there is 
commonly a sort of lid, joined by a very indistinct suture 
to the rest, which can be pushed off, leaving a sufficient 
opening for the egress of the insect. In the pupae of 
many of this tribe this lid is composed of two semicir- 
cular pieces, which can be separately removed. Many 
species seem to be able to force off the lid of their pupa- 
rium, by merely pushing against it with their heads : 
but the common flesh-fly and many other Muscidce, which 
are perhaps too feeble to effect this, or whose puparia 
are stronger than ordinary, are furnished with a very re- 

voi.. in. T 



274' STATES OF INSECTS. 

markable apparatus for this express and apparently sole 
purpose. They are gifted with the power of introducing 
air under the middle part of the head, to which the an- 
tennae are fixed, and of inflating that part into a sort of 
membranous vesicle as big as the head itself; by the action 
of which against the end of the pupa-case, the lid is soon 
forced off. So powerful is this singular lever, that it is 
even sufficient to rupture the fibrous galls in which the 
pupas of the gay-winged Tephritis Car did 2 - are inclosed. 
That it is designed by Creative Wisdom to answer this 
sole purpose seems proved, from its disappearing soon 
after the disclosure of the fly, whose head shortly becomes 
all alike hard. Reaumur suspects that it may also be 
intended to promote the circulation of the insect's fluids ; 
but to me his reasons appear not conclusive b . In one 
instance a mode still more unexpected obtains. The il- 
lustrious naturalist just named found that the fly which 
proceeded from one of the rat-tailed grubs (Elop/iilus 
Latr.) had actually the power of completely reversing its 
situation in its narrow case; and that it then employed its 
tail in pushing off the lid, which other species remove by 
means of their heads c . 

The extrication of insects whose pupas are above 
ground, like those of butterflies, many beetles, flies, &c, 
is comparatively a simple operation. But what, you will 
ask, becomes of those species whose pupas are. concealed 
deep in the earth, or in the heart of the trees on which 
their larva- have fed ? Of this you shall be informed. — 
Coleopterous insects disclosed from pupae thus circum- 

a Reaum. iii. t. xh.f. 12—14. 

b For this whole account, see Reaum. iv. Mem. viii. 

c Ibid. 472. 



STATES OF INSECTS. 275 

stanced, wait until their organs have acquired strength, 
and their elytra are sufficiently hardened to protect their 
filmy wings from damage in forcing their way through 
the earth or wood which covers them. Thus Oryctes ?msi- 
cornis, a rhinoceros beetle common on the Continent, is 
a full month before it reaches the surface of the earth, 
after quitting its puparium. But it is evident that no 
delay would enable lepidopterous or dipterous insects, 
which are without elytra, to make their way out of such 
situations, without irreparable injury to their delicate 
wings. Many of these, therefore, while still within the 
hard case of the pupa, have the precaution, a few days 
previously to their exclusion, to force themselves up to 
the surface of the earth, or, when they reside in the in- 
terior of trees, to the entrance of their hole. This is ef- 
fected by a successive wriggling of the abdominal seg- 
ments, which in several species, of the Coleoptera, Lepi- 
doptera, and Dipt era orders, for this purpose, as has 
been more than once observed a , are furnished with 
sharp points (adminicula), admitting a progressive, but 
not a retrograde motion. The puparia of the great goat- 
moth (Cossus lignipcrda) may be often seen projecting 
from orifices in willow-trees ; and those of the common 
crane-fly (Tipida oleracea) from the surface of the earth, 
to which they have thus made their way from a depth of 
several inches. 

In all the preceding instances the exclusion of the per- 
fect insect is complete, as soon as it has withdrawn itself 
from the puparium. But to a very large number, even 
after this is effected, the arduous task still remains of 

' See above, p. 255—. and Vol. II. p. 301—. 
T 2 



27G STATES OF INSECTS. 

piercing the cocoons of leaves, of thick silk, of tough gum, 
or even of wood, in which the pupae are incased. W e 
can readily conceive how the strong jaws of coleopterous 
and hymenopterous species may be employed to release 
them from their confinement. But what instruments can 
be used for this purpose by moths in a state of great de- 
bility, whose mouth has nothing like jaws— merely a soft 
membranous proboscis ? How shall the silkworm-moth 
(B. Mori) force its way through the close texture of a silken 
ball, through which the finger could not be easily pushed? 
Or the puss-moth {Centra Vinula) pierce the walls of 
its house of glue and wood, which scarcely yield to the 
knife? You will not doubt that these difficulties have been 
foreseen by Infinite Wisdom, and provided against by 
Infinite Power. The egress of moths from their co- 
coons is secured in two ways; — either by some peculiarity 
in the first construction of the cocoon by the caterpillar, 
or by some process which the pupa or perfect insect is 
instructed to perform. As examples of each, several cu- 
rious instances may be cited. 

The larva of the moth which about 1760 made such 
havoc in the province of Angoumois in France, becomes 
a pupa in the interior of the grain of wheat which it has 
excavated ; but the opening by which it first entered is 
not bigger than a pin's point, and is quite insufficient for 
the egress of the moth. How, then, is the latter to force 
its way through the tough skin which surrounds it? The 
larva, previously to assuming the pupa state, gnaws out a 
little circular piece at that end of the grain where the head 
of the future moth would lie, taking care not to detach it 
entirely. At this little door, which is sufficient to pro- 
tect it from intruders, the moth has but to push, when it 



STATES OF INSECTS. 277 

falls down, and leaves a free passage for its exit. A 
contrivance almost similar is adopted by a caterpillar 
which feeds in the interior of the heads of a species of 
teazel (Dipsacus L.), for a minute and interesting history 
of which we are indebted to Bonnet. This caterpillar 
previously to its metamorphosis actually cuts a circular 
opening in the head, sufficiently large for the egress of the 
future moth ; but to secure this sally-port during its long 
sleep, it artfully closes it with fibres of the teazel, closely 
but not strongly glued together a . Another small cater- 
pillar described by the same author, resides in the leaf of 
an ash curiously rolled up into a cone, and then assumes 
the pupa, which is inclosed in a silken cocoon, ingeni- 
ously suspended by two threads like a hammock in the 
middle of its habitation, and of so slight a texture that 
it presents no obstacle to the extrication of the moth. 
It is the closely-joined sides of its leafy dwelling that form 
a barrier, which, were it not for the precaution of the 
larva, would be impenetrable to so small and weak an 
animal. The little provident creature, before its change 
to a pupa, gnaws in the leaf a round opening, taking 
care not to cut through the exterior epidermis. This 
door is to serve the moth for its exit, like that formed by 
the wheat-caterpillar. But in proportion to its bulk its 
verdant apartment is of considerable size. How then 
shall the mothk now the exact place where its outlet has 
been traced ? How, without a clue, shall it discover in 
its dark abode the precise circle which requires only a 
push to throw it down ? Even this is foreseen and pro- 
vided against. Out of twenty positions in which its ham- 

J Bonnet, CEuv. ii. 169. 



278 STATES OF INSECTS. 

mock might have been slung, the caterpillar has been di- 
rected so to place it, that the silken cord that suspends 
the head is fastened close to the side of the door which it 
has previously constructed ; and the moth, guided by this 
fdum ariadneum, at once makes its way out of an apart- 
ment which, but for this contrivance, might have been to 
it a labyrinth as inextricable as that of Minos a . 

The mode in which other caterpillars provide for their 
extrication, when become moths, from their silken co- 
coons, is not less ingenious. Those ol ? Eriogaster lanestris 
(of which I have lately said so much,) and others, form 
oblong cocoons, which, viewed externally, you would at 
the first glance assert were of one solid piece : but on 
examining them more narrowly, you perceive one end of 
them to be a distinct lid, of a size large enough to per- 
mit the moth to issue out ; and that it is kept in its place 
by a few slight threads, easily broken by pressure from 
within b . A few pages back c I mentioned a cocoon formed 
by the larva of Tortrix prasinana, of the shape of a 
boat reversed, composed of two inclined walls fastened 
together at the top and ends. In constructing this cocoon, 
it firmly glues to each other the top and one end, so as to 
form an impermeable suture ; but the other end, at which 
the moth is to issue, though externally it seems as strong 
as the rest, is merely drawn close by a slender thread or 
two fastened on the inside, and easily broken from within. 
And, what is particularly singular in the construction of 
this ingenious habitation, the sides forming the end last 
mentioned, though originally requiring force to draw 

a Bonnet, (JZuvr. ii. 207. b Ros. I. iv. 209. t, Ixiii. ccxii. 

c See above, p, 217. 



STATES OF INSECTS. 279 

them into their required position, become so elastic as to 
close again when the moth has passed between them and 
made her escape ; the cocoon preserving its usual shape, 
even when deprived of its inhabitant a . A similar cocoon 
is constructed by another leaf-rolling caterpillar, that of 
Tortrix chlorana b . Many similar proofs of contrivance 
in the construction of silken cocoons might be adduced, 
but I shall confine myself to one more only — I mean that 
furnished by the flask-shaped brown one of Saturnia Pa- 
vom'a, and some other moths. If you examine one of 
these cocoons, which are common enough in some places 
on the pear-tree or the willow, you will perceive that it 
is generally of a solid tissue of layers of silk almost of 
the texture of parchment; but at the narrow end, or. 
that which may be compared to the neck of the flask, 
that it is composed of a series of loosely-attached longi- 
tudinal threads, converging, like so many bristles, to a 
blunt point, in the middle of which is a circular opening . 
It is through this opening that the moth escapes. The 
silk of its cocoon is of so strong a texture and so closely 
gummed, that had both ends been similarly closed, its 
egress would have been impracticable ; it finds, however, 
no difficulty in forcing its way through the aperture of a 
sort of reversed funnel, formed of converging threads 
that readily yield to pressure from within. But an ob- 
jection will here probably strike you. You will ask, Is 
not this facility of egress purchased at too d&'ar a rate? 
Must not a chrysalis in an open cocoon be exposed to 
the attacks of those ichneumons of which you have said 
so much, and of numerous other enemies, which will find 

a Bonnet, CEuvr. ii. 229. b De Geer ii. 477. 

c Sepp. iv. t. xi./. 8. 



280 STATES OF INSECTS. 

admittance through this vaunted door ? Our caterpillar 
would seem to have foreseen your dilemma ; at least, un- 
der heavenly guidance, she has guarded against the dan- 
ger as effectually as if she had. If you cut open the co- 
coon longitudinally, you will see that within the exterior 
funnel-shaped end, at some distance she has framed a 
second funnel, composed of a similar circular series of 
stiff threads, which, proceeding from the sides of the co- 
coon, converge also to a point, and form a sort of cone 
exactly like the closed peristome of a moss ; or, to use a 
more humble though not less apt illustration, like the 
wires of certain mousetraps a . In this dome not the 
slightest opening is left, and from its arched structure it 
is impenetrable to the most violent efforts of any ma- 
rauders from without; whilst it yields to the slightest 
pressure from within, and allows the egress of the moth 
with the utmost facility. When she has passed through 
it, the elastic threads resume their former position, and 
the empty cocoon presents just the same appearance as 
one still inhabited. Rosel relates with amusing naivete 
how this circumstance puzzled him the first time he wit- 
nessed it : he could scarcely help thinking that there was 
something supernatural in the appearance of one of these 
fine moths in a box in which he had put a cocoon of 
this kind, but in which he could not discover the slight- 
est appearance of any insect having escaped from it, until 
he slit it longitudinally b . But from an observation of 
Meinecken, it appears that these converging threads serve 

a Plate XVII. Fig. 5. N. B. Sepp's figure represents the exterior 
funnel ; and this, which exhibits the cocoon divided longitudinally, 
the interior one, or dome, 

b Itds. I. iv. 31. 



STATES OF INSECTS. 281 

a double purpose ; being necessary to compress the ab- 
domen of the moth as it emerges from the cocoon, which 
forces the fluids to enter the nervures of the wings, and 
give them their proper expansion. For he found, that 
when the pupa is taken out of the cocoon, the moth is 
disclosed at the proper time, but remains always crippled 
in its Avings ; which never expand properly, unless the 
abdomen be compressed with the finger and thumb, so 
as to imitate the natural operation a . 

I am next to give you some account of the second 
mode in which the release of the perfect insect from 
its cocoon is effected — that, namely, wherein its own 
exertions chiefly accomplish the work. I shall from a 
large number select only a few instances. The texture 
of the cocoon of the silkworm-moth is uniform in every 
part, and the layers of silk are equally thick at both 
ends. The moth makes its way out by cutting or 
breaking these threads at the end opposite to its head : 
an operation which, as it destroys the continuity of 
the silk, those who breed these insects are particularly 
careful to guard against, by exposing the cocoon to 
heat sufficient to destroy the included pupa. The ques- 
tion is — What instruments does the moth employ to 
effect this? And this we are not able to answer satis- 
factorily. Malpighi asserts that the animal first wets the 
silk with a liquid calculated to dissolve the gum that 
connects the threads, and then employs its lengthened 
head to push them aside and make an opening 5 . But, as 
Reaumur has observed, besides that so obtuse a part as the 
head of a moth is but ill fitted to act as a wedge, we find 

a Naturf. viii. 133. b Be Bombgc. 29. 



282 STATES OF INSECTS. 

the threads not merely pushed to each side, but actually 
cut asunder. He therefore infers that the eyes, which are 
the only hard organs of the head, are the instruments by 
which the threads are divided — their numerous minute 
facets serving the purpose of a fine file a . It should be 
observed, however, that Mr. Swayne confirms Malpighi's 
asserdon, that the silkworm does not cut, but merely 
pushes aside, the threads of its cocoon ; and he informs 
us that he has proved the fact, by unwinding a pierced 
cocoon, the thread of which was entire b . Yet Reau- 
mur's correctness cannot be suspected : and he affirms, 
that from observation there can scarcely be a doubt that 
most of the threads are broken c ; which is further con- 
firmed in an account of the breeding of silk-worms pub- 
lished in the American Philosophical Transactions : in 
which it is expressly stated, that cocoons out of which 
the fly has escaped, cannot be wound d . Analogy, it 
must be confessed, is against Reaumur's opinion ; since 
other kinds of silkworms make their escape by means of 
ajluid. Thus we are informed by Dr. Roxburgh, that 
Attacus Paphia, when prepared to assume the imago, 
discharges from its mouth a large quantity of liquid, with 
which the upper end of the case is so perfectly softened, 
as to enable the moth to work its way out in a very short 
space of time, — an operation which, he says, is always 
performed in the night e . Perhaps the two opinions mav 
be reconciled, by supposing the silkworm first to moisten 
and then break the threads of its cocoon. In those 
that are of a slighter texture, a mere push against the 

a Reaum. i. 624. *> Trans, of the Society of Arts, vii. 131. 

c Reaum. ubi supr. cl ii. 359. 

e Linn, Trans, vii. 35. 



STATES OF INSECTS. 283 

moistened end is probably sufficient : and hence we find 
in so many newly disclosed moths the hair in that part 
wet, and closely pressed down a . If it be apparently 
difficult for the silkworm-moth to effect an opening in its 
cocoon, how much harder must seem the task of the 
puss-moth (Centra Vinula) to pierce the solid walls of its 
wood- thickened case? Here the eyes are clearly incom- 
petent ; nor could any ordinary fluid assist their opera- 
tion, for the gum which unites the ligneous particles is 
indissoluble in aqueous menstrua. You begin to tremble 
for the fate of the moth incarcerated in such an imper- 
vious dungeon — but without cause : what an aqueous sol- 
vent cannot effect, an acid is competent to ; and with a 
bag of such acid our moth is furnished. The contents of 
this she pours out as soon as she has forced her head 
through the skin of the chrysalis, and upon the opposite 
end of the cocoon. The acid instantly acts upon the 
gum, loosens the cohesiozi of the grains of wood, and a 
very gentle effort suffices to push down what was a mi- 
nute ago so strong a barrier. How admirable and effec- 
tual a provision ! But there is yet another marvel con- 
nected with it. Ask a chemist, of what materials a vessel 
ought to be to contain so potent an acid : he will reply, 
— of glass. Yet our moth has no glass recipient: her 
bottle is a membranous bag ; but of so wonderful a fabric 
as not to be acted upon by a menstruum which a gum, 
apparently of a resinous nature, is unable to resist ! This 
fact can only be explained by the analogous insensibi- 
lity of the stomach to the gastric juice, which in some 
animals can dissolve bone, — and it is equally worthy of 

* Pczold. 171, 



281' STATES OF INSECTS. 

admiration. In both cases, the vitality of the membra- 
nous or fleshy receptacle secures it from the action of 
the included fluid.; but how — who shall explain? 

Ordinarily it is the moth that breaks the cocoon ; but 
in the goat-moth and many Tortrices it is the pupa it- 
self that performs the work, either wholly or partially. 
The pupa of the former is for this purpose furnished 
with sharp points upon the head, capable of effecting 
this object a . The locust-moth, another species of Cossus 
(C. JRobinics Peck), whose history has been admirably 
detailed by Professor Peck, has a different process. " In 
the silk-moth," says he, " and all others which I have 
had opportunity to observe, the chrysalis bursts in the 
cocoon, and the fluid which surrounded the new insect in 
it escaping at the same time, so weakens or dissolves the 
fibre and texture of the silk, that the moth is able to ex-« 
tricate itself, leaving the chrysalis behind it; but this is 
not the manner in the locust-moth. After remaining- till 
all its parts are fully grown and it is ready to quit its 
prison, a certain quantity of exercise is necessary, to 
break the ligaments which attach the moth to the shell 
of the chrysalis, and to loosen the folds of the abdomen. 
In taking this exercise, it can only move the abdomen in 
various directions : as one side of the rinp-s is moved for- 
ward, the hooks in the serrated lines above mentioned 
(the adminicula) take hold of the silk, and prevent their 
sliding back; the next flexure brings forward the oppo- 
site side of the rings, which are prevented by the points 
on that side from slipping back in the same manner, and 
the chrysalis is forced out of the slightly woven extremity 

a Lyonnet 16. 



STATES OF INSECTS. 285 

of the cocoon, and through the silk-lined cavity, till it is 
protruded for about one-third of its length out of the 
opening in the bark, and into the air a ." 

An exception to the general rule — that the rupturing 
of the cocoon is the business of the inclosed insect itself 
— is met with amongst ants ; the workers of which not 
only feed the young, but actually make an aperture in 
their cocoons, cutting the threads with their mandibles 
with admirable dexterity and patience, one by one, at 
the time they are ready to emerge, the precise period for 
which these indefatigable nurses are well aware of, that 
they may meet with no obstacle. Without this aid, the 
young ant would be unable to force its way through the 
strong and dense coating of silk that infolds it b . And a 
proceeding somewhat akin to this was observed by the 
Hon. Captain Percy, R.N., who himself related it tome. 
Being fond of the study of insects, he was in the habit of 
attending to their motions ; and in the beginning of Sep- 
tember 1821 noticed those of a number of female Tipidce, 
probably T. oleracea L., busily engaged in depositing 
their eggs amongst the roots of grass. While observing 
these proceedings, he at the same time saw one quitting 
its pupa-case, which had already by its own efforts got 
its head, thorax, and anterior legs out of it. It was then 
joined by two male flies ; which, with their anal forceps 
and posterior legs taking hold of the pupa-case, appeared 
with their mouths and anterior legs to push the little pri- 
soner upwards, moving her backwards and forwards; 
and as they kept raising her, shifting their hold of the 

a Some Notice of the Insect which destroys the Locust-trees, 70. 
This Memoir is in some American periodical work, of which I have 
not the title. b Huber Fourmis 82. 



286 STATES OF INSECTS. 

skin till she was entirely extricated, when they left her 
to recover her strength by herself. Probably the extreme 
length of the two pair of hind-legs of these animals may 
render such assistance necessary for their extrication. 

There remains yet to be explained under this head the 
manner in which the perfect insect is excluded from cer- 
tain aquatic pupae ; such as those of Phryganea, gnats, 
and one of those Tipulidce that resemble gnats. These 
pupae (perhaps that they may be safe from the attack of 
birds) are destined to remain during the greater part of 
their existence in this state at the bottom of the water. 
But it is obvious that if the perfect insects were there to 
be disclosed, their wings would be wetted, and they would 
be drowned. It is the provision by which this result is 
obviated that now calls for your attention. 

You have already been told that the larvae of Pliry- 
ganea inclose themselves in cases of different materials, 
open at each end a . You have also learned, that in be- 
coming pupae, they secure each end of their cases with a 
grating of silk b . When that change has occurred, they 
remain motionless at the bottom of the water. Now how 
are these pupae, encased in tubes of a greater specific 
gravity than the surrounding fluid, to make their way to 
the surface when the time has arrived for their becoming; 
denizens of the air ? This they accomplish in the follow- 
ing manner : — The pupa is furnished with two strong 
exterior moveable mandibuliform processes, and has the 
power of moving its four anterior legs and antennae while 
in the pupa-case. With these temporary jaws it makes 
an opening in one of the silken doors of its case, forces its 

a Vol. I. p, 4G7. b Vol. II. p. 264. 



STATES OF INSECTS. 287 

way out at that end, and then by moving its legs, the 
cases of which in some species are ciliated for this very 
purpose, swims to the surface, where its skin splits, and 
discloses the included insect. That these jaws are given 
for the express and exclusive purpose of being thus ap- 
plied, seems undeniable. The pupa eats nothing — they 
are therefore in every other point of view superfluous. 
They are given to it alone of all other similar pupae, be- 
cause unnecessary to all others; and they are cast off 
along with the rest of the puparium, the perfect insect 
having no vestige of jaws a . 

The gnat has to undergo its change on the surface of 
the water — How is it to accomplish this without being 
wetted ? In the pupa state they usually remain suspended 
with the posterior end of the body turned downwards : 
but when the period for its change is arrived, it stretches 
it out upon the surface, above which its thorax is elevat- 
ed. Scarcely has it been a moment in this position, than, 
swelling out the interior and anterior parts of the thorax, 
it causes it to split between the two respiratory horns. 
Through this opening the anterior part of the gnat then 
emerges. As soon as the head and trunk are disengaged, 
it proceeds with its labour, and gets out more and more; 
elevating itself so as to appear in the pupnrium like a 
mast in a boat. As it proceeds, the mast is more and 
more elevated and lengthened, till it becomes nearly per- 
pendicular — just as the mast of a boat is gradually raised 
from a nearly horizontal to a vertical position : at this 
period a very small portion of the abdomen remains in 
the puparium. Neither its legs nor wings are of any use 

" De Geer ii. 519. 



288 STATES OF INSECTS. 

in maintaining it in this position. The latter are too soft, 
and, as it were, folded ; and the former are stretched out 
alone the abdomen — the segments of this last part are the 
only agents. The observer who sees how the little boat 
gradually sinks, and how its margin approaches the wa- 
ter, forgets the mischievous insect it contains, which at 
another time he would crush without remorse, and be- 
comes interested for its fate ; especially should wind agi- 
tate the water. A very little is sufficient to drive about 
rapidly the little voyager, since it catches the wind in 
some degree as a sail. If it should be upset, it would be 
all over with it; — and numbers do thus perish. The gnat, 
after having fixed itself thus perpendicularly, draws first 
its two anterior legs out of their case, and moves them 
forward, and next the two intermediate ones ; then in- 
clining itself towards the water, it rests its legs upon it, 
for water is to them a soil sufficiently firm and solid to 
support them, although surcharged with the weight . of 
the insect's body. As soon as it is thus upon the water, 
it is in safety ; its wings unfold themselves and are dried, 
and it flies away. All this is the work of an instant a . 

The pupae of Chironomus plumosus proceed from those 
red worm-like larvae so common throughout the summer 
in tubs of rain-water, &c, described by Reaumur b . 
They are not inclosed in cases, but are of a greater spe- 
cific gravity than the water at the bottom of which they 
reside, until within a few hours of the exclusion of the 
fly. They have the power of swimming, however ; and 
by moving the tail alternately backwards and forwards, 
can slowly raise themselves to the top of the water. But 

a Reaum. iv. 610—. 

b Ibid. v. .30—. t. v./. 1 — 10. See above, p. 153—. 



STATES OF INSECTS. 289 

here occurs a difficulty. For the extrication of the imago 
it is necessary that they should remain quietly suspended 
at the surface ; and moreover that the thorax,*[in which 
the opening for its exit is to be made, should be at least 
level with it : and this is precisely what takes place. If 
you watch one of these pupae when it ascends from the 
bottom, you will see that as soon as it has reached the top 
it remains suspended there motionless ; and that its tho- 
rax is the highest part of the body, and level with the 
surface. Now the question is, in what way this is accom- 
plished ? How can a pupa of greater specific gravity than 
water, remain suspended without motion at its surface? 
and how can its thorax, which is at its heaviest end, be 
kept uppermost ? — By a most singular and beautiful con- 
trivance, which I shall explain ; the more particularly 
because it has escaped Reaumur, and, as far as I know, 
all other entomological observers. The middle of the 

back of the thorax has the property 'of repelling water 

apparently from being covered with some oily secretion. 
Hence, as soon as the pupa has once forced this part of 
its body above the surface, the water is seen to retreat 
from it on all sides, leaving an oval space in the disk, 
which is quite dry. Now though the specific gravity of 
the pupa is greater than that of water, it is but so very 
slightly greater, that the mere attraction of the air to the 
dry part of the thorax, when once exposed to it, is suffi- 
cient to retain it at the surface ; just as a small dry needle 
swims under similar circumstances. That this is a true 
solution of the phenomenon, I am convinced by the re- 
sult of several experiments. If, when the pupa is sus- 
pended at the surface, a drop of water be let fall upon 
the dry portion of the thorax, it instantly sinks to the 
vol. in. u 



290 STATES OF INSECTS. 

bottom, — the thorax, which belongs to the heaviest half, 
being the lowest ; and if the pupa be again brought to the 
surface, so that the fluid is repelled from its disk, it re- 
mains suspended there without effort, as before. Just 
previously to the exclusion of the fly, the dry part of the 
thorax is seen to split in the middle. The air enters, and 
forms a brilliant stratum resembling quicksilver, between 
the body of the insect and its puparium ; and the former 
pushing forth its head and forelegs, like the gnat, rests 
the latter upon the water, and in a few seconds extricates 
itself wholly from its envelope. 

Before I close this letter, I must state a fact connected 
with the subject of it that deserves jto be recorded. It is 
a general rule, that one pupa-case incloses only one insect; 
but Kleesius, a German entomologist, asserts that he 
had once two specimens of Gastropacha quercifolia pro- 
duced from owe pupa; which was large, being full two 
inches long, and one thick. 



LETTER XXXII. 



STATES OF INSECTS. 

IMAGO STATE. 

W HEN the insect has quitted the exuviae of the pupa, it 
has attained the last stage of its existence. It is now 
termed an Imago, or perfect insect; and is capable of 
propagation. 

Just after its exclusion, it is weak, soft, and languid : 
all its parts are covered with moisture ; and, if a winged 
insect, its wings have so little the appearance, either in 
shape, size, or colour, which they are about to assume, 
that it might be taken for a mutilated abortion, rather 
than an animal in the most vigorous stage of life. If it 
be a beetle, its elytra, instead of covering the back of the 
abdomen, are folded over the breast : their substance is 
soft and leathery, and their white colour exhibits no 
traces of the several tints which are to adorn them. If 
the insect be a butterfly or a moth, the wings, instead 
of being of their subsequent amplitude, and variegated 
and painted with a variety of hues and markings, are in 
large species scarcely bigger than the little finger nail, 
falling over the sides of the trunk, and of a dull muddy 
colour, in which no distinct characters can be traced. 

u 2 



29'2 STATES Ot INSECTS. 

If the excluded insect be a bee or a fly, its whole skin is 
white and looks fleshy, and quite unlike the coloured 
hairy crust which it will turn to in an hour or two ; and 
the wings, instead of being a thin, transparent, expand- 
ed film, are contracted into a thick, opaque, wrinkled 



mass. 



These symptoms of debility and imperfection, how- 
ever, in most cases speedily vanish. The insect, fixing 
itself on the spoils of the pupa, or some other convenient 
neighbouring support, first stretches out one organ, and 
then another : the moisture of its skin evaporates, the 
texture becomes firm, the colours come forth in all their 
beauty ; the hairs and scales assume their natural posi- 
tion ; and the wings expanding, extend often to five or 
six times their former size — exhibiting, as if by magic, 
either the thin transparent membranes of the bee or fly, 
or the painted and scaly films of the butterfly or moth, 
or the coloured shells of the beetle. The proceedings 
here described I witnessed very recently with regard to 
a very interesting and beautiful butterfly, the only one of 
its description that Britain has yet been ascertained to 
produce — I mean Pajrilio Machaon. The pupa of this 
being brought to me by a friend early in May this year 
(1822), on the sixteenth of that month I had the pleasure 
to see it leave its puparium. With great care I placed it 
upon my arm, where it kept pacing about for the space of 
more than an hour ; when all its parts appearing conso- 
lidated and developed, and the animal perfect in beauty, 
I secured it, though not without great reluctance, for my 
cabinet — it being the only living specimen of this fine fly 
I had ever seen. To observe how gradual, and yet how 
rapid, was the development of the parts and organs 3 and 



STATES, OF INSECTS. 293 

particularly of the wings, and the perfect coming forth of 
the colours and spots, as the sun gave vigour to it, was a 
most interesting spectacle. At first it was unable to ele- 
vate or even move its wings ; but in proportion as the 
aerial or other fluid was forced by the motions of its trunk 
into their nervures, their numerous corrugations and folds 
gradually yielded to the action, till they had gained their 
greatest extent, and the film between all the nervures be- 
came tense. The ocelli, and spots and bars, which ap- 
peared at first as but germes or rudiments of what they 
were to be, grew with the growing wing, and shone forth 
upon its complete expansion in full magnitude and 
beauty. 

To understand more clearly the cause of this rapid 
expansion and development of the wings, I have before 
explained to you that these organs, though often exceed- 
ingly thin, are always composed of two membranes, hav- 
ing most commonly a number of hollow vessels, miscalled 
nerves, running between them a . These tubes, which, 
after the French Entomologists, I would name nervures, 
contribute as well to the development of the wings, as to 
their subsequent tension. In the pupa, and commonly 
afterwards, the two membranes composing the organs in 
question do not touch each other's inner surface, as they 
afterwards do : there is consequently a space between 
them ; and being moist, and corrugated into a vast num- 
ber of folds like those of a fan, but transverse as well as 
longitudinal, and so minute as to be imperceptible to the 
naked eye, the wings appear much thicker than in the 
end. Now as soon as the insect is disclosed, a fluid enters 

1 See above. Vol. II. p. 346. 



294 STATES OF INSECTS. 

the tubes, and being impelled into their minutest ramifi- 
cations, necessarily expands their folds ; for the nervures 
themselves are folded, and as they gradually extend in 
length with them, the moist membranes attached to them 
are also unfolded and extended. In proportion as this 
takes place, the expanding membranes approach each 
other, and at last, being dried by the action of the atmo- 
sphere, become one. To promote this motion of the fluid, 
seems the object of the agitations which the animal from 
time to time gives to its unexpanded wings. That a kind 
of circulation, or rather an injection of an aqueous fluid 
into these organs, actually takes place, may be ascertained 
by a very simple experiment. If you clip the wings of a 
butterfly during the process of expansion, you will see 
that the nervures are not only hollow, but that, however 
dry and empty they may subsequently be found, they at 
that time actually contain such a fluid a . Swammerdam, 
who appears to have been the first physiologist that paid 
attention to this subject, was of opinion that an aeriform 
as well as an aquiform fluid contributes to produce the 
effect we are considering. He had observed that, if a 
small portion be cut off from the wing of a bee, a fluid of 
the latter kind exuded from its vessels in the form of 
pellucid globules, becoming insensibly drops — which he 
concluded proved the action of the latter ; and he no- 
ticed, also, that the wings were furnished with tracheae, 
which were at that time distended by the injected air ; 
whence he justly surmised, that the action of the air was 
also of great importance to produce the expansion of the 
wing b . And Jurine found that every nervure contains 

a Reaum. i. Mem. ult. De Geer i. 73. Swamm. BM. Nat. i. 184. 
b Swamm. Ihid. 



STATES OF INSECTS. 295 

a trachea, which, proceeding from the interior of the 
trunk in a serpentine direction, follows all the ramifica- 
tion of the nervure, though it does not fill it a . Though 
Reaumur attributes the expansion of the wings chiefly to 
an aqueous fluid, yet he suspects that the air on some 
occasions contributed to it b . 

The wings of the other tribes of insects probably differ 
from the Lepidoptera in the manner in which they are 
folded. It should seem from Reaumur's description, that 
those of some flies, instead of the straight transverse folds 
of the former, have angular or zigzag folds c ; which 
equally shorten the wing. Many Hymenoptera have 
wings without any nervures except the marginal. We 
may conjecture that these are more simply folded, so as 
to render their expansion more easy ; but even in these 
wings there are often tracheae, which appear as spurious 
nervures, and help to effect the purpose we are consi- 
dering. 

The operation of expanding their wings, in by far the 
larger number of insects, takes place gradually as de- 
scribed above ; and, according to their size, is ended in 
five, ten, or fifteen minutes ; in some butterflies half an 

a Jurine Hymenopt. 16. 

b iv. 342. Herold also attributes the rapid expansion of the wing 
to the flow of an aqueous fluid, which he calls blood? into the ner- 
vures, the orifices of which open into the breast. EntwicJceliings. 
der Schmetterl. 101. sect. 100. — M. Chabrier, in his admirable Essai 
sur le Vol des Insectes {Mem. du Mus. 4ieme, ann. 325), having ob- 
served a fluid in the interior of the nervures of the wings of insects, 
thinks it probable that they can introduce it into them and withdraw 
it at their pleasure : the object of which, he conjectures, is either to 
strengthen them and facilitate their unfolding, or to vary the centre 
of gravity in flight, and increase the intensity of the centrifugal force, 

c Ibid. 340. 



29G STATES OF INSECTS. 

hour, in some even an hour. A few species, such as 
Sphinx (Enotherce F., require several hours, or even a 
dav, for this operation ; and, from the distance to which 
they creep before it has taken place, a considerable de- 
gree of motion seems requisite for causing the necessary 
impulse of the expanding fluids a . In a few genera, how- 
ever, as the gnat, the gnat-like Tipulidse, and the Ephe- 
mera, this process is so rapid and instantaneous, that the 
wings are scarcely disengaged from the wing-cases before 
they are fully expanded and fit for flying. These genera 
quit the pupa at the surface of the water, from which, 
after resting upon it for a few moments, they take flight: 
but this would evidently be impracticable, and immersion 
in the fluid, and consequent death, would result, were not 
the general rule in their case deviated from. 

Some species of the last of these genera, Ephemera, 
are distinguished by another peculiarity, unparalleled, as 
far as is known, in the rest of the insect world. After be- 
ing released from the puparium, and making use of their 
expanded wings for flight, often to a considerable di- 
stance, they have yet to undergo another metamorphosis. 
They fix themselves by their claws in a vertical position 
upon some object, and withdraw every part of the body, 
even the legs and wings, from a thin pellicle which has 
inclosed them, as a glove does the fingers ; and so exactly 
do the exuviae, which remain attached to the spot where 
the Ephemera disrobed itself, retain their former figure, 
that I have more than once at first sight mistaken them 
for the perfect insect. You can conceive without diffi- 
culty how the body, and even legs, can be withdrawn 

a Brahra, Insek. ii. 423. 



STATES OF INSECTS. 297 

from their cases ; but you must be puzzled to conjecture 
how the wings, which seem as thin, as much expanded, 
and as rigid as those of a fly, can admit of having any 
sheath stripped from them ; much less how they can be 
withdrawn, as they are, through a small opening at the 
base of the sheath. The fact seems to be, that though 
the outer covering is rigid, the wing inclosed in it, not- 
withstanding it is sometimes more than twenty-four hours 
before the change ensues, is kept moist and pliable. In 
proportion, therefore, as the insect disengages itself from 
the anterior part of the skin, the interior or real wings 
become contracted by a number of plaits into a form 
nearly cylindrical, which readily admits of their being- 
pulled through the opening lately mentioned; and as 
soon as the insect is released from its envelope, the plaits 
unfold, and the wing returns to its former shape and di- 
mensions. Thus our little animal, having bid adieu to 
its shirt and drawers, becomes, but in a very harmless 
sense, a genuine descamisado and sansculotte. It does 
not seem improbable, that the pellicle we have been 
speaking of is analogous to that which, in addition to the 
outer skin, incloses the limbs of Lepidoptera, &c. in the 
pupa state, but which they cast at the same time with the 
puparium, and leave adhering to it a . 

The body of newly-disclosed insects commonly ap- 
pears at first of its full size ; but the aphidivorous flies 
(Syrphus F. &c), and some others, in about a quarter of 
an hour after leaving the pupa become at least twice as 
large as they were at their first appearance : this appa- 
rent sudden growth, which is also noticed by Goedart, 

a Reaum. vi. 505 — . t. xlvi./. 9. Comp. De Geer ii. 627 — . 



298 STATES OF INSECTS. 

Reaumur found to depend upon the expansion of the 
previously compressed segments of the animal by means 
of the included air a . Both in this instance and in that 
of insects whose wings only require expansion, the size 
of the imago often so greatly exceeds that of the pupa, 
that we can scarcely believe our eyes that it should have 
been included in so contracted a space. The pupa of 
one of the beautiful lace-winged flies (Hemerobius Perla) 
is not so big as a small pea, yet the body of the fly is 
nearly half an inch long, and covers, when its wings and 
antennas are expanded, a surface of an inch square b . 

When the development of the perfect insect is com- 
plete, and all its parts and organs have attained the re- 
quisite firmness and solidity c , it immediately begins to 
exercise them in their intended functions; it walks, 
runs, or flies in search of food ; or of the other sex of its 
own species, if it be a male, that it may fulfill the great 
end of its existence in this state — the propagation of its 
kind. Previously to thus launching into the wide world, 
or at least immediately afterwards, almost all insects dis- 
charge from their intestines some drops of an excremen- 
titious fluid, often transparent, and sometimes red. I 
have before related to you the alarm that this last cir- 
cumstance has now and then produced on the minds of 
the ignorant and superstitious d . Whether this excre- 

a Reaum. iii. 378. b Ibid. 385. 

c Insects of the beetle tribe, especially such as undergo their me- 
tamorphosis under ground, in the trunks of trees, &c, are often a 
considerable time after quitting the puparium before their organs 
acquire the requisite hardness to enable them to make their way 
to the surface. Thus, the newly-disclosed imago of Cetonia aurttta 
remains a fortnight under the earth, and that of Lucanus Cervus, ac- 
cording to Rosel, not less than three weeks. 

,J See above, Vol, I. p. 34 — . 



STATES OF INSECTS. 299 

merit is produced indifferently both by males and females 
I cannot positively assert; but a circumstance related 
by Jurine affords some ground for a suspicion that it 
is peculiar to the latter. A specimen of a female of 
Lasiocampa Riibi, when killed emitted some of this 
fluid, which dropped upon the floor : this appeared to 
attract the males to the apartment in which it happened, 
and to the very spot — from whence it maybe conjectured, 
that the scent of the fluid brought them there, and that 
the use of it is to bring the sexes together soon after ex- 
clusion from the pupa a . 

The colour, sculpture, and other peculiarities which 
distinguish insects in this state I shall consider at large 
in another letter, when I treat of their external parts and 
organs. Under the present head I shall confine myself 
to pointing out the characters by which the sexes of many 
species are distinguished from each other; as likewise 
the duration of their life in their perfect state ; together 
with the circumstances on which this duration depends. 

I. Sexual Distinctions. The first general rule that 
may be laid down under this section is, — That among 
insects, contrary to what mostly occurs in vertebrate 
animals, the size of the female is almost constantly larger 
than that of the male. Even in "the larva and pupa states, 
a practised eye can judge, from their greater size, which 
individuals will become females. There are, however, 
some exceptions to this rule. Thus amongst the Coleo- 
ptera } the male DynastidcE, remarkable for their horns, 

a Jurine Hymenopt.9, Note 1. 



300 STATES OF INSFCTS. 

as you may see in D. Aloeus, Antmts, Actaon, &c, as 
likewise those of Lucatius, are larger than the unarmed 
females a . In the Ncuroptera the female Libellulidce are 
sometimes sensibly smaller, and never larger, than their 
males b . In the Hymenoptera the male of the hive-bee, 
but more particularly that of Anthidium manicatum and 
other bees of that genus, is much more robust than the 
other sex c . In the Diptera, the same difference is ob- 
servable in Syrphis Ribesii, and some other aphidivorous 
flies, and also in Scatophaga stercovaria d . And amongst 
the apterous, tribes, we are informed by De Geer that 
the male of Argyroneta aquatica^ which builds an aerial 
palace in the bosom of the waters e , usually exceeds the 
female in bulk f . The reason of this rule seems in some 
degree connected with the office of the female as a mo- 
ther, that sufficient space may be allowed for the vast 
number of eggs she is destined to produce; and it is 
when impregnation has taken place, and the eggs are 
ready for extrusion, that the difference is most sensible. 
In the majority of cases this sexual disproportion is not 
very considerable, but in some few it is enormous. Reau- 
mur mentions a beetle, of which he intended to o-ive the 
history, the male of which is so small compared with the 
female, that a bull not bigger than a sheep, or even a 
hare, set by the side of the largest cow, would aptly con- 
trast with them. This little beetle, he says, has wings 

a Oliv. N. i. t. If. 1. c.f. N. 3. t. m.f. 22. a be. t. v. /. 33. 
t. \\.f. 5. t. xiii./. 124. a b. b Reaum. vi. 423. 

c Kirby Mon.Ap. Angl. ii. t. xvlf. 12, 13. t. xvii./. 10—12. 
d Reaum. iv. 393. e See abovej y 0L> I# 4 ~ 3 _ 

s De Geer vii. 304. 



STATES «r INSECTS. 301 

and elytra, while the giant female has no vestige of either, 
having the upper surface of its body naked and membra- 
nous a . The species to which this illustrious Naturalist 
here alludes, does not appear to have been ascertained. 
The female of many gall-insects [Cocci) is so large in 
comparison with the male, that the latter traverses her 
back as an ample area for a walk b . But this is nothing 
compared with the prodigious difference between the 
sexes of Termes fatale, and other species of white ants, 
whose males are often many thousand times less than the 
females, when the latter are distended with eggs c . Acci- 
dental differences in the size of the sexes sometimes arise: 
as when the female larva has, from any cause, been de- 
prived of its proper supply of food, it will occasionally be 
less than the male. De Geer has stated a circumstance 
with respect to the Aphides that produce galls, that 
should be mentioned under this head — the first, or mo- 
ther female, is larger than any of her progeny ever be- 
come d . 

The second observation that may be generally applied 
to the sexes of insects is, that, size excepted, there is a 
close I'esemblance between them in other respects. But 
to this rule the exceptions are very numerous, and so im- 
portant that it is necessary to specify examples of each 
under distinct heads. 

i. In some species the sexes are either partly or wholly 
of a different colour. Thus, in the order Coleoptera, the 
elytra of the male of Rhagium meridianum F. are testa- 
ceous, and those of the female black. Leptura rubra of 

* Reaum. iv. 30. b Ibid. t. iv./. 15. 

c Sec above, Vol. II. 36. d De Geer iii. 25. 



302 STATES OF INSECTS. 

Linne, with red elytra, is the female of his L. testacea, 
in which they are testaceous. Canlharis dermestoides of 
the same author is the other sex of his Meloe Marci ; 
one of which is chiefly testaceous, and the other black : 
which seems to have so misled Linne, that he placed 
them in different genera. One more instance in this 
order, the female of Cicindela campestris, as was first ob- 
served to me by our friend Sheppard, has a black dot on 
each elytrum, not far from its base near the suture, which 
the male has not. 

Amongst the Orthoptera, the male Locusta F., as Pro- 
fessor Lichtenstein has informed us a , have a fenestrated 
ocellus, which is not to be found in the other sex. I was 
once attending to the proceedings of a Hemipterous spe- 
cies, Pentatoma oleracea Latr., which I found in union : 
the paired insects had white spots, but another individual 
was standing by them, in which the spots were of a san- 
guine hue. I mention this by the way only — the spots 
in the prolific sexes being of the same colour : but might 
not the red spotted one be a neuter ? 

The sexes of many Lepidoptera likewise differ in their 
colour. I must single out a few from a great number of 
instances. The males of Lycoena Argus F. have the up- 
per surface of their anterior wings of a dark blue, while 
in the female it is wholly brown. The wings of the for- 
mer sex of Hypogymna dispar are gray, clouded with 
brown ; but those of the latter are white, with black 
spots. In the brimstone butterfly (Colias Rhamni), which 
is one of the first that appear in the spring, the wings of 
the male are yellow— of the female whitish. In the com- 

■ 1 Linn. Tram. iv. 51 — . 



STATES OF INSECTS. 303 

mon orange-tip [Pieris Cardamines F.), one sex has not 
the orange tip to the upper wings : and, to name no more, 
the male of Lyccena dispar, one of our rarest and most 
beautiful butterflies, has only a single black spot in the 
disk of its fulgid wings ; while in the other sex, the pri- 
mary pair have nine, and the secondary are black, with 
a transverse orange fascia near the posterior margin. 
But the most remarkable difference in this respect ob- 
servable in the insects of the order in question, takes 
place in a tribe, of which only one species is certainly 
known to inhabit Britain — I mean the Papiliones Equites 
of Linne : what he has called his Trojani and Achivi in 
some instances have proved only different sexes of the 
same species. Mr. MacLeay's rich cabinet affords a sin- 
gular instance confirming this assertion ; — a specimen of 
a Papilio is divided longitudinally, the right hand ^ide 
being male, and the left hand female. The former be- 
longs to P. Polycaon, a Grecian, the latter to P. Lao- 
docus, a Trojan. An instance of two Grecians thus united 
is recorded in the Encyclopedie Methodique, as exhibited 
in a specimen preserved in the; Museum of Natural Hi- 
story at Paris; which on the right hand side is P. Ulysses, 
on the left P. Diomedes a . 

In the Neuroptera, the Libellulidce are remarkable for 
the differences of colour in the sexes. In the common 
Libellula depressa, which you may see hawking over 
every pool, the abdomen of the male is usually slate- 
colour, while that of his partner is yellow, but with darker 
side-spots. Reaumur, however, noticed some males that 
were of the same colour with the females b . Schelver 

a ix. 65. n. 110. h vi. 423. 



304 STATES OF INSECTS, 

observed, when he put the skins of Libellula depressa into 
water, that the colours common to both sexes were in 
the substance of the skin, and remained fixed; while 
those that were peculiar to one could be taken off with a 
hair-pencil, and coloured the water: which therefore 
were superficial, and, as it were, laid on a . The yellow 
males, therefore, that Reaumur observed, were probably 
such as had the superficial blue colour which distinguishes 
them washed off! In Calepteryx Virgo Leach, the for- 
mer are of a lovely silky blue, and the latter green. In 
Agrions F. nature sports infinitely in the colours of the 
sexes. 

In the order Hymenoptera there are often differences 
equally great; the sexes of many of the Ichneumons and 
Saw-flies are of quite different colours. The former tribe 
Linne has divided into sections, from the white annul us 
observable in the antennae of some, and from the colour 
of their scutellum : but these are often merely sexual 
characters b . The male of Anthophora retusa Latr., a 
kind of wild bee, is wholly black, the female wholly gray, 
and of so very different an aspect that they were long 
regarded as distinct species ; a mistake which has likewise 
occurred with regard to the sexes of Osmia ccerulescens, 
another bee, of which the male has a bronzed and the 
female a violet abdomen c . The nose of male Andrence 
Latr. is often yellow, or white, as in A, litfemoi~rhoidalis — 
when that of the female is black d . The labrum also is often 
of a different colour in the sexes, as in Ceratina Latr. 

a Entomologische, &c. 224. 

b De Geer ii. 847. 850. Jarine Hymenopt. 100. 

c Kirby Mori. Ap. Angl. ii. 296. 264, 

d Ibid, ii, 142—. 144, 147, 148 3 &c, 



STATES OF INSECTS. 305 

In the Diptera, Aptera, Arachnida, &c, I am not aware 
of any striking difference in the colours of the sexes. 

ii. The sexes of insects vary (but more rarely than in 
colour) in their sculpture also, and pubescence. Thus the 
elytra of the females of many of the larger water-beetles 
(Dytiscus) are deeply furrowed, while those of the males 
are quite smooth and level a . The thorax of the female 
in several species of Colymbetes of the same tribe, as 
C. Hybneri and transversalis, on each side has several 
tortuous impressed lines or scratches, like net-work, 
which are not to be discovered in the male. Hyphydrus 
gibbus Latr., which differs solely from H. ovalis {JDytis- 
cus ovalis Illig.) in being thickly covered with minute 
impressed puncta, is, from the observation of the Rev. 
R. Sheppard, the other sex of this last, with which he 
has taken it coupled ; and it is by no means improbable 
that Hydroporus picipes {Dytiscus punctatus Marsh.) and 
H. lineatus, — between which, as Gyllenhal has justly ob- 
served, the same difference only exists, — are in like man- 
ner sexual varieties. With respect to pubescence, I have 
not much to say. Another aquatic beetle, Acilius sulcatus 
Leach, has not only its elytra sulcated, but the furrows 
of these, and a transverse one of the thorax, are thickly 
set with hair; while the male is smooth, and quite naked. 
Particular care seems to have been taken by the Creator, 
that when all the above inhabitants of the water are paired, 
the male should be able to fix himself so firmly, by means 

a A remarkable anomalous exception to this rule sometimes oc- 
curs in the female of D. margbialis, which has smooth elytra like the 
male (Gyll. Ins. Suec. i. 467 — )• I have this variety from the Rev. 
Mr. Dalton, of Copgrove, Yorkshire. 

VOL. III. X 



306 STATES OF INSECTS. 

of his remarkable anterior tarsi, (which I shall afterwards 
describe,) and these asperities, &c. in the upper surface 
of his mate, as not to be displaced by the fluctuations of 
that element, the reluctance of the coy female, or any 
other slighter cause. 

In a moth called the ghost (Hepialus Humuli), the 
posterior tibia of the male is densely bearded, but not of 
the female 3 . — Some Hymenoptera, as Ammophila Kirb. 
and Stigmus Jurine, have the upper lip of the male clothed 
with silver pile, while that of the female is not so orna- 
mented. The legs of some bees are distinguished in the 
sexes by a difference in their clothing. That observable 
in those of the hive-bee has been before noticed b . In 
Andrena of Latreille c the posterior tibia of the female is 
covered externally with a dense brush of hairs, for col- 
lecting the pollen ; and the posterior legs at their base 
have a curled lock of hair — which are not to be found in 
the male d . In Dasypoda, Melecta, Anthophora, Centris, 
Epicharis, &c. of the same author, the first joint of the 
tarsus of the female, and in Xylocopa almost the w T hole 
tarsus, is also similarly signalized from that of the other 
sex. In Bombns, as in the hive-bee, the posterior tibiae 
of the females and neuters are furnished with a basket of 
hairs for carrying their pollen paste, which you will in 
vain look for in the male e . The latter, however, in some 
species of this tribe are distinguished from the former by 
the longer hairs of their legs, but not in the posterior 
ones. Thus, in Anthophora retusa the first joints of the 

a De Geer i. t. vn.f. 11. 

b See above, Vol. II. 125, Note b . 

c Melitta ** c. Kirby Mm. Ap. Angl. i. 140. 

d Ibid. t. iv. f. 10 a. b.f. 14. ' Ibid. t. xiii./. 20. a. 



STATES OF INSECTS. 207 

intermediate tarsus are bearded internally with a thin 
fringe of long hairs, and the first externally with a tri- 
angular one of short ones at the apex : but what is most 
remarkable, the last or unguicular joint, which in al- 
most every other bee is naked, is on both sides fringed 
with long hairs a . In that remarkable genus Acanthopus 
Iliig., of which the male only is known, the first and last 
joint of the intermediate tarsus have a dense external 
brush of stiff hairs, which probably is also a sexual cha- 
racter b . Another sexual kind of clothing is exhibited 
by the females of those bees that have their labrum or 
upper-lip inflexed (Megachile Latr.) c . Their abdomen 
is covered underneath with a brush of stiff hairs, involved 
in which they carry the pollen they collect. In the males 
of some of this tribe, as of M. Willughbiella, the first four 
joints of the anterior tarsus on their inner side have a 
long dense fringe of incurved hairs d : a circumstance 
also to be found in the same sex of Xylocopa latipes, in 
which the claw-joint also is bearded e . In Andrena Latr. 
the last dorsal segment of the abdomen of the same sex is 
fringed, while that of the male is naked f . In the humble- 
bees (Bombus), the mandibles of the male are bearded 
with curled hairs, while those of the females and neuters 
are without them. Some bees, as Andrena and Halictus 
Latr., have the anus of the female bearded, and that of the 
male naked : in some Bombyces the reverse takes place. 



A Kirby Mon. Ap. Angl. i. t. xi. Apis #*. d. 2. x. /3./. 18 a. b. c. d. 
b Coquebert Illustr. Icon. i. t. vi.f. 6. 

c Kirby Mon. Ap. Angl. i. Apis **. c. 1. «. #*. c. 1. /3. **. c. 2. x. 
**. c. 2. /3. **. c. 2. y. **. c. 2. 1. 

d Ibid. t. viii./. 28. f. g. « Christ. Hymenopt. t. iv.f. 3. b. 

f Kirby Mon. Ap. Angl. i. t. iv. Melitta *#. c.f. 1. a. 

x 2 



30S STATES OF INSECTS. 

iii. With regard to the general shape of their body, 
the male and female usually resemble each other : but 
there are some exceptions to this rule. The male of the 
hive-bee is much thicker and more clumsy than either 
the female or the worker ; but in Halktus Latr. the males 
are nearly cylindrical in shape, and very narrow ; while 
the other sex are oblong or ovate, especially their abdo- 
men : and in Andrena Latr. the former are much slen- 
derer than the females, and of a more lanceolate shape. 
But a still more striking difference in this respect be- 
tween the sexes is exhibited by some species of the genus 
Ptinus F., in which the male is long and slender, and the 
female short and thick. This, in more than one instance, 
has occasioned them to be mistaken for distinct insects : 
thus, P. Lickenwn and P. similis, P. ovatus and P. tes- 
taceus, of Mr. Marsham, are mere sexual varieties. But 
the most entire abalienation of shape at present known, 
is that which distinguishes the male from the female 
Coccus ; these are so completely dissimilar as scarcely to 
have any part in common. In Bombyx vestita F., and 
others of the same family, while the males are of the or- 
dinary conformation of the order, the females are without 
even the slightest rudiments of wings ; they have no an- 
tennae, the legs are extremely short, not longer than 
those of the caterpillar ; and the body is entirely desti- 
tute of scales, so that they altogether assume the exact 
appearance of hexapod larvae a . A conformation nearly 
similar takes place in the female of Tinea Lichenella ; but 
in this the feet are longer, and the anus is furnished with 
a long retractile ovipositor b . 

a Scheven Naturfors. stk. xx. 65. t. n.f. 4. Compare Ibid. x. 101. 
b Reaum. iii. t. xv.f. IS, 19, 



STATES OF INSECTS. 309 

iv. In many cases, the structure of particular parts and 
organs of the body differs in the sexes. As the facts con- 
nected with this part of our present subject are extremely 
numerous and various, it will be convenient to subdivide 
it, and consider the sexual characters that distinguish — 
the Head, Trunk, and Abdomen of insects, and their se- 
veral appendages. 

1. The Head. This part in some females is consider- 
ably larger than it is in the male. This is the case with 
the ants, and several other Hymenoptera ,• while in some 
Andrence, as A. Jicemorrhoidalis, and Staphylinida?, as 
St. olens, that of the male is the largest. But in none is 
the difference more conspicuous than in the stag-beetle 
{JLucanus); in which genus the male not only exceeds the 
female in the length of his mandibles, but also greatly 
in the size and dimensions of his head. In the Apion 
genus, the rostrum of the female is generally longer and 
slenderer than that of her mate; and in Brentus, the 
rostrum of one sex (probably the male) is long and fili- 
form, while in the other it is thick and short. This is 
particularly visible in B. dispar and maxillosus a , &c. 

One of the most striking distinctions of the males in 
this part of their body, are those threatening horns, usu- 
ally hollow, with which the heads of many of the male 
lamellicorn insects and some others are armed, and which 
give them some resemblance to many of the larger qua- 
drupeds. Many are unicorns, and have their head armed 
with only a single horn ; which in some, as in Oryctes 
Illig., Dynastcs Endymion b , &c. is very short ; in others, 

> Oliv. no. 84. Brentus, t. If. \.b. c. I. li.f. 17. a. b. 
b Oliv. no. o. ScarabcBus, t. xviii./, 169. 



310 STATES OF INSECTS. 

very long, as in Dynastes Enema, Pan, Elephas a . In 
one, again, it is thick and robust; as in the clumsy Dy- 
nastes Action b : in another very slender, as in Ontho- 
phagus spinifer c . With respect to its direction in Ele- 
phastomus proboscideus MacLeay, it is horizontal d and 
straight ; in Phaleria cornuta horizontal and broken, or 
the apex turning outwards and forming an angle with the 
base e ; in Dynastes Hercules horizontal, and recurved 
at the apex f ; in D. Action, Elepkas, and Typhon, re- 
curving from the base. In Geotrupes dispar it is re- 
curved, so that its point exactly coincides with that of 
the porrected thoracic horn, with which it forms a kind of 
forceps s. In Copris lunaris F. and Diaperis horrida, the 
horn is nearly upright h . In Onthophagus Xiphias it is di- 
lated at the base, and reclining upon the thorax ; and at 
the apex attenuated, and bending forwards, or nodding. 
In Passalus comutus it rises a little, and then bends wholly 
forwards. In Dynastes Milon, a most remarkable beetle, 
it slopes backwards in a waving line ' ; and in Onthophagus 
spinifer it is recurved and reclining. — In speaking of the 
direction of the horn, you must recollect that it will vary 
in proportion as the head varies from a horizontal posi- 
tion : so that an upright horn will become inclined or 
reclined, as the head bends forwards or backwards ; but 
I speak of it as it appears when the head is horizontal. 

a Oliv. ScarabcBus, t.xii.f 114. /. xv.f. 1.38. a. 

h Ibid. t. w.f. 33. >■ ibid. t. xii./. 112. 

'' Linn. Trans, vi. t. xix.f. 12. i. xx.f. 2. 

" Oliv. no. 57- Tenebrio, I. i.f. 2. 

f Oliv. ubi supr. No. 3. t. i.f. 1. 

* Oliv. no. 3. *.iii./.20. a. 

'' Ibid. no. 5.5. Diaperis, I. i.f. 3. 

1 Oliv, ScarabcBus, I. xx./". 185. 



STATES OF INSECTS. 311 

Again, it varies in its teeth or branches. In Dynastes 
Hercules it is armed with several teeth. In D. Elephas 
and ActdEon it has only one large one at its upper base a . 
In D. Milon it is serrated above. In D. Alcides, Tityus, 
JEgeon, Copris lunaris, Sec. the horn is unarmed and sim- 
ple at the apex. In D. Oromedon, Gedeon, Enema, 
Actceon and congeners, it is bifid. In some the horn is 
at first a broad lamina or ridge, which terminates in two 
branches, as in Onthophagus Vacca. In this the branches 
are straight; but in another undescribed species in my 
cabinet (O. Aries Kirby, MS.) they are first bent in- 
wards, and then at the apex a little recurved : and in 
D. dichotomies it is divided into two short branches, each 
of which is bifid b . Other males emulate the bull, the 
he-goat, or the stag, in having a pair of horns on their 
head. In Onthophagus Taurus, these arms in their curva- 
ture exactly resemble those of the first of these animals c . 
In Goliathus pidverulentus, the straight, robust, diverging, 
sharp horns are not unlike those of some of the goat or 
gazel tribe. I have a beautiful little specimen in my ca- 
binet, (I believe collected by Mr. Abbott of George,) in 
which the horns have a lateral tooth, or short branch, 
like those of a stag ; and which I have therefore named 
O. cervicornis. In O. Vacca, Camelus, &c. the horns are 
very short, and nearly perpendicular. In the male of 

a As Dynastes Action, Elephas, TypJwn, &c differ from D. Her- 
cules, &c, not only in their general habits, horns, &c, but also in 
their maxillae and labium, — the former in D. Actaeon being simple, 
and in D. Hercules toothed, and the labium of the first bilobed at 
the apex, and in the last entire and acute, — according to the modern 
system they ought, therefore, to be considered as distinct genera. 
I would restrict the name Dynastes to D. Hercules and its affinities: 
D. Actcson, &c. I would call Megasoma. 

b Oliv. Scarabccus, t. xvii./. 156'. c Ibid. t. viii./. fio. 



312 STATES OF INSECTS. 

Copris Midas, the two longer perpendicular horns have a 
deep cavity between them, which, together with its black 
colour, give it a most demoniac aspect ; so that you would 
think it more aptly representative of a Beelzebub or Beel- 
zebul than a Midas a , or than Phanams Beelzebul MacL. 
A similar cavity is between the occipital horns of Dia~ 
peris hcemorrhoidalis Payk. Some species of Rynchanus, 
as R, Taurus, have a pair of long horns upon the rostrum 
of the male, the rudiments only of which are to be traced 
in the female b . Other species go beyond any known 
quadrupeds in the number of horns that arm their heads. 
ThusZ) itomus calydonitisTionelli, belonging to CarabusI^., 
has three equal horns c . The same number distinguishes 
Onthophagus Bonasus ; but the intermediate one is very 
short. In Goliathus Polyphemus the middle horn, on the 
contrary, is much longer and thicker than the lateral 
ones, and forked at the apex ; so that it looks as if it had 
four of these weapons d . A little Diaper is [D. viridipen- 
nis F.), a native of Carolina, has four horns upon the 
head of the male ; namely, two long ones on the occiput, 
and two short dentiform ones on the nose. In a species 
nearly related to this, sent me by Professor Peck from 
New England, there is a cavity between the two occipi- 
tal horns. The same number distinguishes Onthophagus 
quadrieornis (Copris F.), The situation also of the 
horns varies : In some it is in the middle of the head, 
as Oryctes nasicornis, Copris lunar is, &c. : in others, as 
in Onthophagus nuchicornis, Xiphias, &c. it is a process 

a This insect is beautifully figured in M. Latreille's Insectes sacres 
dcs Egijptiens,f. 11. See Luke xi. 15. Heb.b)n]by2 Domi?ws stercoris. 
11 Oliv. no. 83. 160. t. vi./. 60. g.l.v.f. 45. $ ? 
'■ Ibid, no. 36. t, ilf. 12. a [bid, no. 6. 1, vilf. 6L 



STATES OF INSECTS. 313 

of the occiput or hind-head ; and in O. Oryx F. the two 
horns proceed from the anterior part of the head. In 
the other sex, in insects the head of whose males is armed 
with horns, they are usually replaced by mere tubercles, 
or very short elevations, as you may see in the female of 
Copris lunaris; or by transverse ridges, as in the Ontho- 
phagi: or else the head is without arms, and quite smooth, 
as in Diape? , is, Phaleria, &c. What may be the use of 
these extraordinary appendages, as well as those on the 
thorax, and in some cases on the abdomen, (which I shall 
mention afterwards), to the males, has not yet been ascer- 
tained. Whether the individuals of this sex are more 
exposed to the attack of birds and other enemies, in con- 
sequence of being more on the wing than the females, 
and are therefore thus provided with numerous project- 
ing points for defence, is a question worth considering a . 
It is the only probable conjecture on the cui bono of these 
arms that I can at present make. Under this head I 
ought to notice the remarkable membranous process of 
an obovate shape, which like an umbrella covers the 
head of Acheta umbraculata F. b Whether the sharp 
curved horns which arm this part in another Acheta 
figured by Stoll c , in an incumbent posture, with their 
point towards the mouth, are a sexual distinction, we are 
not informed, — probably they are. 

The organs of the head also present many sexual di- 

« See above, Vol. II. 224—. 

b Coquebert Illustr. Icon. hi. t. xxi./. 2. 

c Stoll Cigales, t. xviilf. a b c. Grillons t.iv. /. 16 — 18. This sin- 
gular animal, which was found by Mr. Patterson at the Cape of 
Good Hope, is stated to be an aquatic; and affords the only known 
instance of an Orthoptervus insect inhabiting the waters. The GryL 
lotalpa loves the vicinity of water. 



31-t STATES OF INSECTS. 

stinctions. The upper lip (labrum) in Halicius Latr., a 
tribe of wild bees, in the female is furnished with an in- 
flexed appendage, which is not discoverable in that of 
the male a ; and the shape of this lip in Sphecodes Latr. 
differs in the sexes b . Perhaps the horn or tubercle ob- 
servable on this part of some female Nomadce F. c may 
be wanting in the male. 

The under-lip (labium) — taken in a restricted sense for 
that central part from which emerge the labial palpi, and 
which is often considered as the mentum, — does not offer 
any striking variations in the sexes. One, however, is 
of importance, as it helps to prove which are the true 
female Lucani. In the male the labium is emarginate, 
in the female it is intire. This may be seen both in 
L. Cervus and femoratus, and probably in other species. 
The sculpture also is different, the lip being smooth in 
the former and covered with excavated puncta in the lat- 
ter. The tongue (lingua or ligida) of the sexes is usually 
the same ; except in the hive-bee, in which that of the 
neuters is longer than that of the male and female. 

The upper-jaws (mandibulce), however, often afford 
striking sexual characters. The enormous protended 
ones of the common stag-beetle (Lucanus Cervus) attract 
the attention of the most incurious observer ; and these 
are now generally allowed to be of this description. 
Geoffroy and Mr. Marsham, indeed, have asserted that 
they have taken in coitu those with long mandibles : but 
as these males are pugnacious, and attack each other with 
great fury, as Mr. Sheppard informs me, it is not impro- 
bable that these gentlemen may have mistaken a battle 

a Mon. Ap. Angl. i. Melitta **. b. 139. I. ii./. 4—6. 

h Ibid. **. a./. 4, 5. r Ibid. Apis *. b. ]!)0-. /. v./. 18 b. ■ 



STATES OF INSECTS. 315 

for an amour : since not only have those with long man- 
dibles been often taken united with those that have short 
ones a , but the same difference obtains in the sexes of 
other species. This is particularly observable in Lucanus 
Jemoratus, of which I received from Brazil many speci- 
mens agreeing in every respect except in this, that one 
had short and the other very long mandibles. These 
organs vary in different specimens, as to the number of 
their teeth and branches. They are singularly robust in 
L. Alces h ; but in none more threatening than in L. Ele- 
plias c , in which they curve outwards and downwards. 
In Mr. W. MacLeay's genus Pholidotus, they are almost 
parallel to each other, and curve downwards ; in Lucanus 
nebulosus Kirby, they assume a contrary direction d ; as they 
do likewise in Lamprima Latr. e In Lucanus Capreolus 
the points close over each other f . In Lethrus F. in the 
female, but not the male, the mandible is armed below with 
a long incurved horn. In Lucanus serricornis they form 
a complete forceps g . In Siagonium quadricorne Kirby h 
the mandible is furnished at its base with an exterior 
horn, which is probably a sexual distinction. The male 
of Synagris cor?iuta, a kind of wasp, is still more conspi- 
cuous in this respect ; for from the upper side of the base 
of its straight slender mandibles proceed a pair of crooked, 
decurved, tortuous, sharp horns, not only longer than 



a By Rosel, by a friend of De Geer's, and by M. Marechal. De 
Geer iv. 331 — . Nouv. Did. d'Hist. Nat. xviii. 225. 

b Oliv. no. i. Lucanus, t. \\.f. 3. c Ibid. t. iii./. 7- 

d Linn. Trans, xii. 410. t. xxlf. 12. e Ibid. vi. 185. t. xx.f. 1. 

f Oliv. ubi sup?\ t. ii./. 4. 

f Regne Animal, iii. t. x'm.f. 3. 

h See Vol. I. Plate 1. Fig. 3. 



316 STATES OF INSECTS. 

the mandible, but than the head itself a . Many sexual 
differences are observable in the mandibles of the va- 
rious tribes of bees (Anthophila Lain). Thus, in Collelcs 
Latr. the male mandible is more distinctly biclentate at 
the apex than the female b : in Sphecodes Latr. and others, 
the reverse of this takes place c . Where these organs in 
both sexes are toothed at the apex, they often vary in the 
number of teeth. Thus, the female of Megachile centime 
cularis Latr. has four teeth at the apex of its mandible, 
while the male has only two d . In M. Wittughbiella, 
though the mandibles of both sexes have four teeth, yet 
those of the male are sharp, and the two external ones 
the longest ; while those of his mate are obtuse, and all 
nearly equal in length e . In Anthidium manicatum. Latr., 
the former has only three teeth, while the latter has five f . 
The differences in this respect in the hive-bee have been 
before noticed S; those of the humble-bees (Bombus Latr.) 
are strikingly distinguished from each other ; the female 
mandible being very stout and wide, constricted in the 
middle, and furrowed on its outer surface ; and the male, 
on the contrary, very slender at the apex, dilated at the 
base, and without furrows h . 

Of all the organs of the head, none seem so little sub- 
ject to sexual variation as the under-jaws (mazilUe) '. I 

a Christ. Hymenopt. i. xviii./. 2. 

b Man. Ap. Angl. i. Melilta * a. t. If. 5. $ . 7. <? . 

c Ibid. Melitta **. a. t. ii./. 6. ? . 7. <? . and **. b. i. m.f. 3. ? . 4. <y . 

d Ibid. i. viii./. 11. <j> . 12. J . 

e Ibid.'i. t.ym.f. 9. $ . 10. <?. 

f Ibid. Apis **. c. 2. /3. t. ix.f. 6. $ . 7. $, 

R See above, Vol. II. 125. Note h . 

h Mon. Ap. Angl. ubi supr. i. xiii./. 13. ^ , 14. j. 

j MacLeaj^ Hor. Enlomolos. i—, 



STATES OF INSECTS. 317 

can bring forward only one striking instance of it, and 
some degree of doubt rests even upon that. In the genus 
Nemognatha of Illiger, the maxillae of the male are elon- 
gated, narrow, setiform, and often involute or spiral, like 
those of a bee or a butterfly. But that this is peculiar 
to the males is at present only surmised a . I possess se- 
veral species of the genus, all of which are distinguished 
by long maxillae ; though in some they are as long as 
the body, and in others scarcely half that length. Gna- 
thmm Kirby is similarly characterized b . 

The maxillary palpi occasionally differ in the sexes. 
In Cerccoma those of the female are filiform, while the 
two intermediate joints of those of the other sex are much 
thicker than the first and the last c . In Hylcecetus and 
Lymexylon, those of the male are still more remarkable : 
they are pendent, the last joint very large, and laciniated 
so as to form a tuft d . The female ones grow gradually 
larger towards the end, but are not at all divided there e . 
The palpi of male spiders are of a very different struc- 
ture from those of the other sex, term mating in a very 
complex incrassated piece, which has been supposed to 
contain the organ of generation; but this, according 
to Treviranus, is a mistaken idea — that organ feeing, as 
usual, to be found in the abdomen f . In the common 
gnat the palpi of the male are as long as the proboscis, 
consist of five joints, and at the end are tufted with hairs; 
while those of the female are scarcely one-fourth of its 

a JV. Diet. d'Hist. Nat. xxii. 488: 

b Linn, Trans, xii. 425—. I. xxii./. 6. c Plate XXVI. Fig. 2. 
d Ibid. Fig. 3. e Oliv. no. xxv. Lymexylon, t. \.f. 1. 

f De Geer vii.249— . t.xiv.f. 20, 21. Treviranus Arachnid. 36—. 
t. ii./. 16. a h c. t. iv./*. 35—37. 



318 STATES OF INSECTS. 

length, have only three joints, and are not tufted. Whe- 
ther the labial palpi in any genus differ in the sexes, I 
cannot affirm with certainty : I have not, however, ob- 
served any such variation in them. 

I shall next mention some organs of the head, in which 
the difference between the sexes is often very striking 
and peculiar. You will readily conjecture that I am 
speaking of the antenna. And here the advantage seems 
wholly on the side of the males : since in them these 
wonderful instruments of unknown sensations are not 
only more complex, but usually more elegant, than 
those of the other sex. You will pardon me, therefore, 
if I enlarge a little more than ordinary upon a subject so 
full of interest, and say something upon the differences 
observable between the sexes — in the shape, magnitude, 
and length, number of articulations, ramification and 
plumage, and individual joints of their antennae. 

With regard to their shape, variations are sometimes 
observable between the antennas of the sexes; but this 
principally occurs in the Hymenoptera order, For in- 
stance, those of Chelostoma maxillosa, a small bee that 
deposits its eggs in little holes in posts and rails, are cla- 
vate in the female and filiform in the male a — a circum- 
stance that distinguishes in some degree those of Sphe- 
codes, Halictus, and Andrena of Latreille, three other 
genera of wild-bees b . In Dinetus Jur. the male antennae 
are moniliform at the base, and filiform at the apex ; the 
female, on the contrary, are entirely filiform c . 

a Mon. Ap. Angl. i. Apis **. c. 2. y. t. ix.f. 7. 5 . 9. $. 

b Ibid. Melitta •*. a. t, ii./. 8. $ . 9. S . and **. b. t. ni.f. 6. 5 . 

7. <?. **. c t. iv.f. 11. 5 . 12. <?. 
e Jurine Hymenopt. t.ll.f.2, 



STATES OF INSECTS. 319 

The antennae of the sexes also sometimes differ in 
magnitude and length. This is the case in the three ge- 
nera of wild bees just mentioned ; those of the female be- 
ing thicker than those of the male, while these last are 
longer than the former. But in this tribe the males of 
the Fabrician genus Eucera are most remarkable for their 
long antennas a . With regard to the different length of 
these organs in the sexes, no insects are more distinguished 
than some species of the capricorn-beetles {Cerambyx L.). 
In Lamia Sutor the male antennae are twice the length of 
the female ; and in another Brazilian species in my cabi- 
net, related to L. annulata (Stenocorus F.), they are thrice 
their length. Some of the Anthribi F. approach the 
Cerambycidcc, not only in some other characters, but also 
in this circumstance : — thus the antennae of A. albinus, a 
native of Britain, are vastly longer in the male than in 
the female; and in A. cinereus (Macrocephalus Oliv.) b , 
which I suspect to be of the former sex, they are as long 
nearly as is usual in the tribe just named, called in France 
capricorn-beetles. 

I may here observe, that sometimes in the sexes a dif- 
ference is also to be found in the direction or flexure of 
their antennae. Thus in Scolia F., Pepsis F. &c, in the 
males the antennae are nearly straight, but in the females 
convolute or subspiral. The reverse of this takes place 
in Epipone spinipes, a kind of wasp, and its affinities; and 
Systropha Illig., a kind of bee : for in these the male an- 
tenna is convolute at the apex c , and the female straight. 
In the various tribes of bees (Anthophila Latr.), these 

a Mori. Ap. Angl. i. Apis **. d. 1. t. x.f. 7- 
b Oliv. no. 80. Macrocephalus, t. i.f. 2. 
c Latr. Gen. Crust, et Ins. iv. 15b', 



320 STATES OF INSECTS. 

oro-ans in the latter are what is denominated broken, the 
main body of the antenna forming an angle with the first 
joints : but in the former this does not take place. 

The antennae of the sexes do not always agree in the 
number of joints. In the bees, and many other Hymeno- 
ptera, the male has one more joint than the female; as is 
the case also in (Edemera notata {Cantharis acuta Marsh.). 
In Pteronus Laricis, a kind of saw-fly, the latter has only 
sixteen joints in its antennas, while the former has twenty- 
four a . In Rhipicera marginata, a beetle, the beautiful 
antennae of the male consist of thirty-two joints, while 
the female has no more than eleven ! In Chelojius Jur. 
the male, on the contrary, has the smallest number of 
joints, namely sixteen ; while the female has twenty- 
five b . 

In nothing do the sexes differ more materially than in 
the ramification of these organs, and their plumage. By 
attending to this, you may often detect the sexes in an 
instant ; since the antennae of the males in numerous in- 
stances are much more complex than those of the females. 
For what end the Creator has so distinguished them is not 
quite clear ; but most probably this complex structure is 
for the purpose of receiving from the atmosphere informa- 
tion of the station of the female. A tendency to branching 
will be found in the antennas of some males, in tribes where 
these organs are usually perfectly simple in both sexes. 
Thus, in the male of Chelostoma maxillosa, — mistaken for 
another species by Linne, which he names Apisjlorisom- 
nis t — the intermediate joints on their inner side project 
into an angle c ; and those of the same sex of the common 

■ l Jurine Hymenopt. 61. t. xi.f. 8. b Ibid. 289. 

e Mon. Ap. Aug/, i. t. ix. Apis **. c. 2. y.f. 9. 



STATES OF INSECTS. 321 

hornet, by means of a central sinus, have two obtuse 
teeth on each. With regard to more direct ramiflca- 
tions, some male antennae terminate in a fork, or two 
branches. This is the case with Hylotoma furcata Latr., 
a saw-fly a ; and the peacock-louse (Nirmus Pavonis 
Herm.) b . Others, again, have three lateral branches, 
as in Eulophus Geoffr. a little parasite, the male anten- 
nae of which send forth a hairy external and rather long 
branch, from the base of the fourth, fifth, and sixth 
joints c . In Elater Jlabellicornis L., the eight last joints 
are flabellate, or elongated and flat, resembling the sticks 
of a fan in the male d ; in the female they are shorter, and 
more properly may take their denomination from the 
teeth of a comb. In Lamjpyris Latreillii Kirby, the an- 
tennae of the former are flabellate on both sides, while 
those of the latter are little more than serrate e . These 
organs are extremely beautiful in the males of the Rhi- 
jpicerce of Latreille. In JR. marginata K. they consist of 
thirty-two joints, from thirty of which issues a branch, 
the first very short, but the rest gradually increasing in 
length as they approach the middle of the antenna ; then 
gradually decreasing to the end, so as to represent an 
expanded fan f . But in none are they altogether so re- 
markable as in those moths that Linne denominates 
Bombyces Attaci, and some others. In these, in the males, 
these organs in their contour are lanceolate, and every 
joint is furnished with a couple of parallel equal branches 
on each side g . In the females these branches are shorter 

a Plate XI. Fig. 19. b Plate V. Fig. 3. 

« Plate XI. Fig. 18. d Ibid. Fig. 17- 

e Plate XXV. Fig. 11. Linn. Trans.xn. t. xxi./. 4. a. 
f Ibid.f. 3. g Plate XXV. Fig. 22, 

VOL. III. Y 



322 STATES OF INSECTS. 

on the whole, and alternately one long and one short; but 
in some, as Saturnia Pavonia, there is only one short 
branch or tooth on each joint in this sex a . In Bombyx re- 
galls &c. only the first part of the antenna is so branched ; 
and those of the female are setaceous and without branches. 
In B. versicolor, &c. there is only one branch from each 
side on every joint ; those of the female being much 
shorter than those of the male. The latter sex of Ptero- 
nus Laricls Jur., a saw-fly, afford an example of a dif- 
ferent structure, the antennae on one side sending forth 
a branch from every joint but the two first; but on the 
other side, the nine or ten last joints also are without a 
branch. The female antenna is serrated b . In another 
of this tribe, Pterygopterus clnctus Klug, the male an- 
tenna resembles a single-toothed comb, being branched 
only on one side : that of the female, like the former in- 
stance, is serrated c . Whether the remarkable antennae 
that distinguish the known individuals of the genus Phen- 
godes [Lampyrls plumosa F.) is a sexual character has 
not been ascertained ; but it is not improbable that it 
may be, as in other Lampyrldce. A pair of delicate 
flexile and almost convolute plumose branches proceeds 
from the apex of each joint except the basal ones, which 
have something the air of cirri, and give a more than 
usual degree of lightness and elegance to these organs d . 
Other antenna?, especially in the Dlptera order, assume 
an appearance of plumes — not from the branches that pro- 
ceed from them, but from the fine long hairs that beset 
and adorn them. These are universally indications of the 

a De Geer i. t. xix / 11, 12. '> Jurine Hymenopt. t. vi./. 8. 
c Plate XXV. Fig. 25,26. ll Ibid. Fig. 4. 



STATES OF INSECTS. 323 

male sex, those of the females being generally compa- 
ratively naked. If you take the common gnat, you will 
find that the antennae of one individual are thickly fringed 
on each side, and tufted at the end with fine long hairs, 
while in the other only four or five placed at intervals in 
a whorl are to be perceived a . In Chironomus Meig., a 
kind of Tipida L., resembling a gnat, the male antennae 
are beset on all sides with the finest hairs, and resemble 
a beautiful plume b , while the females to the unarmed 
eye appear naked. Even in some Hyfnenoptera, the an- 
tennae of the males are thus feathered, in a less degree : 
for instance, in Hylotoma Latr. c Whether the tufts 
and fringes which ornament, in a remarkable manner, 
the antennae of many Cerambycidm d , are sexual charac- 
ters, is not certainly known. 

We are now to consider other sexual differences in 
these organs, resulting from the size or configuration of 
one or more individual joints. To begin with the first 
joint, or scapus. In many of the Hymenoptera, particu- 
larly the Anthophila Latr., this is elongated, and the re- 
maining joints form an angle with it in the females : while 
in the other sex it is much shorter, and in the same line 
with the rest of the antennae ; and in Hylceus dilatatus 
(Melitta dilatata Kirby) the first joint in the male is di- 
lated and shaped something like a patella e . In Mala- 
chins bipustulatus, &c. the sex just mentioned is pecu- 
liarly distinguished by a white excrescence on the first 

a Reaum. iv. t. xl./. 2. a a. 3 . t. xxxix./. 3. $ . In the last the 
hairs are too conspicuous. 

b Plate XII. Fig. 24. c Jurine Uj/menopt. t. vi.f, 3 

* Plate XII. Fig. 25, 26. XXV. Fig. 17, 32? 
e Ibid. Fig. 12. 

Y 2 



§24 STATES OF INSECTS. 

four joints of the organs in question, most conspicuous 
in the second and fourth. The antennas of male Cero- 
coma are not very different a . Mr. Marsham has de- 
scribed a little Haltica under the name of Chrysomela 
nodicornis, from a peculiarity of the same sex not to be 
found in the other. The fourth joint is very large and 
obtriangular ; in the female it is merely longer than the 
rest. In H. Brassier and quadripustulata the fifth joint 
is larger and longer than all but the first in the male, in 
their females it is only longer. In some moths {Hermi- 
nia Latr., Cr ambus F.) there is also a knot in the middle 
of the male antennae b . In Noterus, a water-beetle, the 
six intermediate joints are thicker than the rest, begin- 
ning from the fourth, and the last but one ends internally 
in a truncated tooth. The fifth and two following joints 
in the male antennae of Meloe are larger than the rest, 
which distinguishes them, as well as a remarkable bend 
observable at that part c . 

Variations of the kind we are considering are also ob- 
servable in the clava, or knob, in which antennae often 
terminate. You have doubtless observed that the la- 
mellated clava of the antennae of the common cockchafer 
is much longer and more conspicuous in some individuals 
than in others — the long clava belongs to the male d . In 
another species, M. Fullo, that of this sex is nine or ten 
times the length of that of the other. In Colymbetes 
serricornis, a water-beetle, the male has a serrated clava 
of four joints. In Dorcatoma dresdensis e , and also Eno- 
■plium damicome, two beetles, it is nearly branched in the 

1 Plate XL Fig. 22. * N. Diet. cTHist. Nat. xiv. 395. 

« Plate XII. Fig. 7. d Plate XXV. Fig. 1. 

e Ibid. Fig. 21. 



STATES OF INSECTS. 325 

male, but much less so in the female. In a little destruc- 
tive beetle, common in our houses (Attagenus Pellio), 
in the latter it is very short, but in the former it is very 
long, and nearly formed by a single joint. In Eurhinus 
Kirby, a New Holland genus of the weevil-tribe, in the 
male the last joint, also, is much longer than it is in the 
female a . These examples will give you some idea of the 
principal variations that take place in the antennae of the 
sexes, and of the wonderful diversity of forms in this re- 
spect to which mere sexuality gives rise amongst insects. 
Inthe eyes, or stemmata, this diversity is less remarkable. 
Latreille has described two ants, Formica contracta and 
coeca, in the neuter of which he could discover no eyes b : 
in the former, the female, however, had large ones. The 
male he appears not to have known, but it probably was 
not destitute of these organs ; of the latter he was ac- 
quainted only with the workers. The neuter of Myr- 
mica rubra, another ant, has no ocelli or stemmata, 
although the male and female are provided with them c . 
They are discoverable only in the former sex of that sin- 
gular insect related to the ants, Mutilla europcea. Other 
insects differ in the size of the eyes of their sexes. In 
the hive-bee, and some Ephemerce, the eyes of the drone 
or male are much larger than those of the worker and 
female, and also meet at the vertex, having their stemmata 
below the conflux; whereas in these latter they are 
widely distant d . In Stratyomis, Tabanus, and many other 

a Linn. Trans.xii. t. xxii./. 8. e. <?./. 5 . 
b Hist. Nat. des Fourmis, 195—. 270—. 
c De Geer ii. 1094. 

d Ibid. 650. Mon. Ap. Angl. i. t. xi. Apis xx. e. \.f. 2. J. t. xii, 
/. 3. ? . 



326 STATES OF INSECTS. 

two-winged flies, the male eyes meet at some point below 
the stemmata, and above the antennae. In the former 
they touch more at an angle ; for the vertex forming a 
narrow isosceles triangle, and for the anterior part of the 
face one nearly equilateral : while those of the female are 
separated by a considerable interval. In Heptatoma 
and Hcematopota in that sex, a similar interval obtains ; 
while in the other, after forming a minute short triangle, 
they unite for a considerable space, and then diverging, 
form the face. This is also the case in Tabanus ; but in 
the female, the space that intervenes between the poste- 
i"ior part of the eyes is much narrower than in these two 
cognate genera of the horse-flies. In some others of 
this order, as Musca Latr., the eyes of the male do not 
touch, but approach posteriorly much nearer to each 
other than those of the other sex. In a few instances 
the sexes vary even in the number of their eyes, as well 
as the size. This occurs in some species of Ephemera L. 
(E. diptera, &c), in which the male, besides the com- 
mon lateral ones, has two large and striking interme- 
diate eyes, that sit upon vertical pillars or footstalks 3 . 

2. The Trunk, The thorax of many coleopterous 
males, especially of the Dynaslidce and Copridaz amongst 
the petalocerous tribes, exhibits very striking differences 
from that of the female. In many Lucani the lateral 
angle is more prominent. In Antliia it is bilobed poste- 
riorly, while in the last-mentioned sex it is entire b . In 
Phanasus carnifcx MacLeay (Copris F.) it is elevated into 
a plane triangular space, with the vertex of the triangle 

• Plate XXVI. Fig. 33. De Geer ii. 651. 659. 
b Voet Colcopt. I f. xxxix.f. 47, 48. ?. . 46. $ . 



STATES OF INSECTS. 327 

pointing to the head; but in the female it is convex, with 
an anterior abbreviated transverse ridge a . 

In a large proportion terrific horns, often hollow, like 
those of the head lately noticed, arm the thorax of the 
male, of which you will usually only discover the rudi- 
ments in the other sex. In the first place, some are uni- 
corns, or armed only with a single thoracic horn, which 
frequently, in conjunction with the thorax itself, not a little 
resembles a tunnel reversed : of this description are Dy- 
nastes Hermles, Tityus, Gedeon, Enema, &c. b In the 
three first this horn is porrected, or nearly in the same line 
with the body ; but in the last, and D. Pan, it forms an 
angle with it ; and in D. JEgeon it is nearly vertical c . 
In D. Hercules it is very long; in D. Alcides d and Tityus 
very short ; in the two last, and in Oxyielus tricornis 
which is similarly armed, it is undivided at the apex; 
but in D. Gedeon, Pan, bilobus, &c. e it is bifid or bilobed. 
It is usually rather slender, but in D. CJwrinaeus f and 
bilobus, it is very stout and wide. In D. claviger it is 
hastate at the apex s. In D. hastatus it is short and 
truncated h . Others, again, have two thoracic horns. 
In Coipris nemestrinus these are discoidal, diverging, and 
inclining forwards '. In Phanaeus jloriger^ they are late- 
ral, triangular, and incline towards each other, with, as 
it were, a deep basin between them. In P. splendidulus 
they sink into two longitudinal ridges, most elevated 

a Oliv. no. 3. t. vi. f. 46. a. $ . b. 5 . 

b Ibid, t.i.f. 1. iv. x.f. 31. xi./. 102. xn.f. 114. 

c Ibid. t. xxvi./. 219. d Ibid, t If. 2. 

e Ibid. t. xxiii./. 35. f Ibid. t. iif. 7- 

6 Ibid. t. v./. 40. h Ibid. xix./. 1 75. 

s Ibid.*, xii./. 115. 

k Cojiris floiiger Kirby in Linn. Trans, xii. 396. 



328 STATES OF INSECTS. 

posteriorly, with an intervening valley a . In P. belhcasus 
they are posterior, compressed, truncated, and erhargi- 
nate at the apex, and include a basin b . In Copris Sabaus 
they are merely two acute prominences c . — Three horns 
distinguish the thorax of many. In D. Aloeus d and its 
affinities, they are arranged in a triangle, whose vertex 
is towards the head. In D. Antaus e these horns are 
nearly equal in length, and undivided at the apex. In 
D. Titanus f the anterior horn is longer than the rest, 
and bifid at the apex ; in D. Atlas and Endymion &, both 
of which have a horn on the head, it is much shorter. 
In others, as in Megasoma Kirby, the vertex of the tri- 
angle is towards the anus. In M. Typkon " it is longer 
than the anterior ones, and bifid at the apex ; in M. la- 
nigerum they are equal in length '. In M. Elephas and 
Actceon * it is merely an elevation of the thorax j in the 
last almost obsolete. In Geotrupes Typhceus, common 
on our heaths, the anterior of this part is armed by three 
horizontal horns, the intermediate one being the short- 
est l . Copris lunar is also, another of our own beetles, 
has three short posterior thoracic horns, two lateral and 
triangular ones, and a transverse intermediate elevation, 
with a notch in the middle m . In Dynastes Neptunus the 
horns are porrected, the middle one being very long, and 
the lateral ones short n . In D. Gcryon the point of the la- 

* Oliv. no. 3. t. n.f. 18. » Ibid. t. xxii./. 32. 
« Ibid. t. ix./. 85. d Ibid. t. iii./,22. 

« Ibid. t. xiii./. 124. a. f Ibid, t.v.f. 38. 

e Ibid. t. xxviii./. 242. t. xviii./. 169. 

h Ibid. t. xvi./. 152. * Ibid. t. xxviii./. 247. 

* Ibid. t. xv. f. 138. a. t. v.f. 33. 
1 Samouelle's Compend. t. \.f. 1. 

'" Oliv. no. 3. t. v.f. 36. a. n Schon. Synon. It. I. 



STATES OF INSECTS. 329 

teral horns is towards the anus, and the base of the in- 
termediate one covers the scutellum a . Others have four 
of these singular arms : this is the case with one of our 
rarest beetles, Bolbocerus mobilicornis K., which has four 
dentiform horns, the intermediate pair being the short- 
est, arranged in a transverse line on the anterior part of 
the thorax b . In B. quadridens these are merely teeth. 
In Phanceus Faunus c it has two lateral, elongated, com- 
pressed, truncate, horizontal horns, and two intermediate 
teeth. Dynastes Milon has a still greater number of 
horns on the thorax of the male, there being two lateral 
anterior ones and three posterior ones — the intermediate 
being the longest d ; and Copris Anterior Fabricius and 
Olivier describe as having a many-toothed thorax ; and 
from the figure of the latter e , the male appears to have 
seven prominences. 

But the males of insects are not only occasionally di- 
stinguished by these dorsal arms — in a few instances they 
are also furnished with pectoral ones. The illustrious 
traveller Humboldt found in South America a species 
of weevil (Cryptorhynchus Spicidator Humb.), the breast 
of which was armed with a pair of long projecting horns; 
and I possess both sexes of four species, three at least 
from Brazil, that exhibit in one individual the same cha- 
racter. One, concerning the country of which I am un- 
certain, recedes somewhat from the type of form of the 
rest, and comes very near that of Rynchccnus Strix F. f 
In the individual which I take to be C. Spiculator, the 
pectoral horns are very long, curving upwards at the 

a Oliv. no. 3. t. xxiv./. 208, b Ibid. t. x ./. 88. 

e Ibid./ 87- d Ibid. t. xx.f. 185. 

e Ibid. t. vi.f. 42. a. ' Ibid. n. 83. Curciilio t.xx'ii.f. 295. 



330 STATES OF INSECTS. 

apex, and nearly in a horizontal position ; while in the 
three others they are much shorter, and inclined towards 
the horizon. The males of some species of liynchites, as 
R. Bacchus and Populi a , are also armed with a pair of 
lateral horns or spines, which may be termed pectoral 
rather than dorsal. 

I shall now advert to the sexual characters that are to 
be found in the instruments of motion attached to the 
trunk — beginning with those for fight. In the female of 
the common glow-worm [Lampyris noctiluca) not the 
slightest vestige of elytra or wings is visible, and it re- 
sembles a larva rather than a perfect insect ; yet its mate 
is a true beetle furnished with both. The same circum- 
stance distinguishes the female cockroach (Blatta) and 
is more universally prevalent in that genus than in Lam- 
pyris, in which a large number of females have both ely- 
tra and wings. The males of Bombyx antiqua and Gono- 
stigma, and of many other moths, have wings of the usual 
ample dimensions, while those of their females are merely 
rudiments. This is the case, also, with some of the Ich- 
ncumonidce b . In the tribes of Ants, Termites, &c. the 
neuters or workers are without wings. Amongst the 
plant-lice (Aphides) there are individuals of both sexes, 
some of which have wings, and others not c . Amongst 
the Coleoptera, the female of Tenebrio Molitor, the com- 
mon meal-worm, has elytra and no wings; while the 
male has both d . — Sometimes these organs vary in size 
in the sexes : thus in Aradus Betulce F., a kind of bug, 
the hemelytra and wings are narrower and shorter in the 

a Oliv. no. 81. Attclabus t. n.f. 27. b. 28. 

b De Gecr ii. t xxxi./. 18—22. r - Ibid. iii. 21. 

d Lesser L i. 185. 



STATES OF INSECTS. 331 

female than in the male a . In the genus Blaps F., the 
mucro that arms the apex of each elytrum is longer in 
the former sex than in the. latter. In AteucJms gibbo- 
sus F., a dung-beetle, the elytra have a basal gibbosity 
near the suture in one sex that does not obtain in the 
other. In the Orthoptera order, the sexes are often to 
be known, almost at first sight, by a difference in the 
veining and areolets of the wings ; but upon this I en- 
larged so fully when I treated of the sounds produced by 
insects, that it is not necessary to repeat what I have 
said; which observation also applies to the drums which 
distinguish the male Cicadce b . The wings of some but- 
terflies, and of most moths and hawkmoths {Sphinx L.), 
are furnished with a singular apparatus for keeping them 
steady, and the under-wing from passing over the upper 
in flight. This appears to have been first noticed by 
Moses Harris, and was afterwards more fully explained 
by M. Esprit Gioma c . From the base of the under-wing 
proceeds a strong bristle, received by an annulus or 
socket, which springing between the two principal ner- 
vures of the upper-wing terminates in the disk of the 
wing : in this annulus the bristle moves to and fro, and 
prevents the displacement of the under-wing. This ap- 
paratus is perfect only in the males, which alone have 
occasion for long flights ; the females, though they have 
often several bristles, having no annulus d . 

The other instruments of motion, the legs, also differ in 
the sexes. In some instances they are disproportionably 
long. This is particularly the case with the anterior pair 

a De Geer iii. 308. b Sec above, Vol. II. 394—. 

c Linn. Trans, i. 145. 135—. 
d Ibid t xiii.y. 1. 2. <? . 3. $ . 



332 STATES OF INSECTS. 

of some beetles, as Macropus longimanus, Scar abatis longi- 
manus L., in which they are so long as to make the males, 
of these individuals rather inconvenient in a cabinet. 
Amongst British beetles Clytra longimana and Curcuho 
longimanus Marsh, are also remarkable in this respect. 
In some other males the middle pair are the longest; as in 
Anthophora retusa Latr., a kind of wild-bee a . There are 
two known instances of remarkably long posterior legs in 
the Capricorn tribe, which I suspect belong to the present 
head. One is Saperdahirtipes 01iv. b , in which the hind-legs 
are longer than the whole body, and adorned with a sin- 
gular tuft of hairs ; and the other a Clytus, I think, which 
Mr. MacLeay purchased from the late Mr. Marsham's 
collection, in which the hind-legs are not only very long, 
but have tarsi convolute, like some antenna?. From ana- 
logy I should affirm that these were the characters of 
male insects. 

To come to the parts of legs. Sometimes the coxa of 
the last mentioned sex are distinguished from those of 
the female by being armed by a mucro or spine. Thus 
the male of Megachile Willughbiella, and others of that 
tribe, have such a spine on the inner sides of the anterior 
coxa c . The Trochanter also of some differs sexually ; 
and you will find that the posterior one of the male in 
Anthidium manicatum is of a different shape from what 
it is in the female d . In Spkodrus leucopththalmus, one of 
the beetles called black dors, in one sex the same tro- 



a Mon. Ap. Angl i. t. xi. Apis **, a. 2. «. ji.f. 18. 
b Oliv. no. 68. Saperda t. l.f. 8. 
« Mon. Ap. Angl. i. t. viii./. 28. c. 
d Ibid. t. ix. Apis **. c. 2. (l.f. 12. 



STATES OF INSECTS. 333 

chanter terminates in a long mucro or spine a , and in the 
other it is rounded at the apex. 

Peculiar characters in their thighs also often indicate 

o 

different sexes. In Primus damicornis there is a short 
spine at the apex of the anterior ones in the female that 
is not in the male ; while in Macropus longimanus, at their 
base externally the male is armed with a mucro, which I 
cannot find in the female b . In Scarabmcs longimanus L. 
this thigh is furnished with two teeth c . — The interme- 
diate thighs also sometimes differ. In an Onitis from 
China, a variety perhaps of O. Sphinx, those in the male 
are dolabriform, and in the other sex of the ordinary 
shape. In Odynerus spinipes they have on their lower 
side two sinuses, so as to give them the appearance of 
being toothed. The posterior thighs are sometimes in- 
crassated in the male, and not in the female. This you 
will see in a weevil, not uncommon, Apoderus Betulce, 
and also in many species of Cimbex F., a kind of saw-fly ; 
and the same circumstance distinguishes the latter sex in 
many species of Lygceus F., a kind of bug : I discovered 
this from L. cruciger, of which I have both the sexes ; and 
from Stoll's figure of L. Pharaonis d . In some of these 
the female thighs are enormously large. A remarkable 
variation in this respect is observable in the coleopterous 
genus (Edemera (Necydalis L.). In CE. Podagrarice these 
limbs are incrassated in one sex and not in the other e ; 
in CE. carulea they are so in both sexes; and in CE. ceram- 

a Clairv. Ent. Helv. ii. t. xii./. B. 

b Oliv. Ins. no. 66. t. hi. iv./. 12. c Ibid. no. 3. t. iv.f. 27. 

d Punaiscs, t. m.f. 20. 

e Mr. Marsham has made two species of this from this circum- 
stance, viz. Necydalis Podagrarice and simplex. 



334- STATES OF INSECTS. 

boides in neither. In Pelecinus Potycerator F., one of 
the Ichneumon tribe, or an insect very near it from Bra- 
zil, these thighs in the female are armed with two spines 
underneath, which are not in the male. 

The anterior tibia in Scarabceus longimanus L. differ 
remarkably in the sexes. In the female they are of the 
ordinary shape, and serrated externally ; but in the male 
they are very long, incurved, and without teeth or serra- 
tures a . In the males of the genus Onitis F. they are bent 
like a bow, and acute at the end ; but in the females they 
are formed on the common type b . In Hisp.a spinipes F. 
they are armed internally with a crooked spine c . But 
the most extraordinary sexual variation of this joint of 
the leg may be seen in the male of Crabro cribarius F. 
and several other species of the same family, in which 
these tibiae are dilated externally into a concavo-convex 
plate, or rather have one fixed to them and part of the 
thigh, of an irregular and somewhat angular shape d , 
with numerous transparent dots, so as not badly to re- 
semble a sieve : whence the trivial name of the species. 
Rolander, who first described it, fancied that this plate 
was really perforated, and that by means of it the animal 
actually sifted the pollen ; but it is most probably for 
sexual purposes. In another species, the plate is orna- 
mented with transparent converging streaks. In the 
bee-tribes (Anthophila Latr.) the posteriw tibia of the 
working sex is generally bigger than the corresponding 
part in their more idle partners : this is particularly con- 

a Oliv. n. 3. t. xxvii./. 27. £ . and t. \v.f. 27. <? • 
b Ibid. t. vii./. 58. <?./. 57. $ . 
c Ibid. n. 95. Hispa t. If. 4. Plate XXVII. Fig. 24. 
d Plate XV. Fig. 3. 



STATES OF INSECTS. 335 

spicuous in the genus Euglossa, in the females of which 
this part is triangular, very broad towards the apex, and 
fitted for carrying a large mass of pollen paste. The 
tibiae of the males of some Lepidoptera are remarkable in 
this respect. That of Hepialus Hamuli is much more 
hairy ; but in H. Hectus it is a dilated mis-shapen mass, 
without a tarsus, and with long scales pendent from the 
disk a . Differences of this kind also occur in the calcaria 
or spurs that arm the apex of the tibiae of a large num- 
ber of insects. Thus in Acanthopus Klug, a singular 
bee, in the male the spur of the intermediate leg is dilated 
at the apex, and armed with six strong spines, the inner 
one larger than the rest 5 . 

But the part of the leg in which the sexes most vary 
is the tarsus ; and this variation takes place both in the 
number of the joints, and their form and circumstances. 
The first case has been observed only with regard to cer- 
tain species of Cryptopliagus Herbst, as C. Jumatus, &c. 
in which the female is pentamerous, or having^*? joints 
in all the tarsi ; and the male heteromerous, or havingjive 
joints in the two anterior pairs, and only four in die 
posterior c . With respect to the form of the tarsal joints, 
the sexes more frequently differ ; and by inspecting this 
part, especially in the predaceous and carnivorous Co- 
leoptera, you may often, without further examination, 
ascertain whether any individual is male or female. 
Even in the slender-footed Cicindelidce^ the three first 
joints of the anterior tarsus of the male are more dilated 
than the two last, and covered underneath with a brush 

a DeGeeri./. vii./. 14, 15. 

h Coquebert Ittust. Icon. i. t. vi / 6. Plate XXVII. Fig. 32. 

Illig. Mag, iv. 214. Gyllenhal. Insect Suec. i. 168. 



fi36 STATES OF INSFXTS. 

of stiffish hair; in the female all are equally slender, and 
not so hairy. In Carabus, Feronia, &c. Latr. the four first 
joints of these tarsi in the males are dilated, and furnished 
with a brush or cushion : in the Silp/iidce, also, the same 
circumstance takes place. In Harpalus Latr., and Sil- 
pha americana, the four anterior ones are similarly formed 
in this respect. But one of the most remarkable sexual 
characters, in this tribe of insects, that distinguish the 
males, are those orbicular patella?, furnished below with 
suckers of various sizes, and formed by the three first 
joints of the tarsus, which are to be met with in the Dy- 
tiscidtf, &c. ; but as I shall have occasion to treat of these 
more fully in another Letter, I shall only allude to them 
now. The second pair of tarsi have in these also the 
three first joints dilated and cushioned a . In Hydro- 
philus piceus, another water-beetle, the fifth joint of the 
tarsus is dilated externally, so as to form nearly an equi- 
lateral triangle b . Christian, a German writer on the Hy- 
menoptera, has described some very singular appendages 
which he observed on the first joint of the four posterior 
tarsi of Xylocopa latipes F. These were battledore- 
shaped membranaceous laminae, with a reticulated sur- 
face, of a pale colour ; which were fixed in pairs by the 
intervention of a footstalk to the above joint, on which 
they sometimes amounted to more than a hundred : the 
use of which, he conjectures, is the collection of pollen c . 
I possess two specimens of this bee ; one has none of 
these appendages, and on the other I can discover them 
only in one of the tarsi — from which circumstance I am 



a Plate XV. Fig. 9. b Ibid§ FlGt 8# 

e Christ. Hymenopt. 118. t. iv./. 3. 



STATES OF INSECTS. 387 

led to conjecture that, like the supposed Clavarice that 
were imagined to grow on some humble-bees, but which 
are now ascertained to be the anthers of flowers — these 
also belong to the kingdom of Flora, and are spoils which 
the bee in question has filched from the blossom of some 
plant. The individuals that have been thus circum- 
stanced are males ; whether the female is guilty of simi- 
lar spoliations is not known. In my specimen there are 
no traces of them. In many bees, the first joint of the 
posterior tarsi is much larger in the females and workers 
than in the males; but in the hive-bee this joint is larg- 
est in the latter a . In Beris clavipes and Empis nigra, 
two flies, the joint in question is large and thick in the 
male, but slender in the female. The penultimate tarsal 
joint in the posterior legs is dilated internally, and termi- 
nates in a mucro in one sex of Anoplognathus Dj/tiscoi- 
des of Mr. W. MacLeay b . In some insects the anterior 
tarsus of the males has been supposed to be altogether 
wanting : I allude to the petalocerous genus Onitis F. ; 
but I have a specimen of Onitis Apelles of this sex, or a 
species nearly related to it, in which one of these tarsi 
is to be found c ; which, though very slender, consists of 
five joints, and is armed with a double claw : from which 
circumstance it may, I think, be concluded, that although, 
as in Phanceus, these tarsi are very minute, they are not 
wanting. What renders this more probable is, a circum- 
stance which every collector of insects, who has many 
specimens of Mr. W. MacLeay's Scarabceidce in his ca» 
binet, must have noticed : namely, that in all, except Co- 

a Mon. Ap. Angl. i. t. xi. Apis **. e. 1. $ ./. 8. e. and t. xii. **. 
e. 1. neut./. 19. c. 

» Hor. Entoviolog. 144. c Plate XXVII. Fig. 45. a. 

VOL. III. Z 



338 STATES OF INSECTS. 

pris and Onthophagus, the anterior tarsi are usually broken 
off. Out of seventeen individuals of Scarabceus MacLeay 
in my own, not a single one has a relic of an anterior tar- 
sus ; and scarcely one in a much greater number of Pha- 
ncei. The tarsus in question in the nobler sex in Crabro, 
at least in C. cribrarius and its affinities, is also very short, 
especially the three intermediate joints ; but at the same 
time very broad and flat. In the species just named, the 
external claw forms a kind of hook ; and in the rest it is 
considerably longer than the other a . The claws, indeed, 
occasionally vary in the sexes in other Hymenoptera : 
thus in Melecta Latr., a kind of bee, in the female they 
are intire, but in the male they are furnished with an in- 
ternal submembranaceous tooth or process b . In Cceli- 
oxys conica and others, those of the latter sex are bifid at 
the apex, but those of the former acute c . In Megachile, 
the male claw is as in the instance just mentioned, while 
the female has a lateral tooth d ; and a similar character 
distinguishes the sexes in the hive-bee e . 

3. The abdomen. This part affords many external 
sexual characters, whether we consider its general shape; 
the number of segments that compose it ; its base, mid- 
dle, or extremity. 

In general shape it often differs in the sexes. Thus, 
the abdomen of female Tipulce is lanceolate; that of the 
male cylindrical, and thickest at the extremity f . In 



a De Geer ii. t. xxviii./. 2. 

b Man. Ap. Angl. i. t. v. Apis **, a.f. 10. $ . 11. $ . 
c Ibid. t. vii. Apis**, c. 1. cc. 17- ? • 18. $. 
d Ibid. t.Vm.f. 30. e?. 31. ? • 

e Ibid. t. xi. Apis **. e. 1. mas./. 9. t. xii. Apis **. e. 1. fern. /. 9. 
and neut,/. 22. ( De Geer vi. t. xviii./. 12, 13. 



STATES OF INSECTS. 339 

Molorchus F. it is convex above in the former, and flat 
in the latter, — the female of this beetle not unaptly repre- 
senting some female Ichneumons in this respect, and the 
male their males a . In Andrena it is oblong in the one, 
and lanceolate in the other. In the hive-bee the drones 
have a thick, obtuse, and rather long abdomen ; in the 
females it is long, and nearly represents an inverted cone; 
and in the workers a three-sided figure, or prism. 

The number of segments, also, is generally different in 
the two sexes — the male having one more than the female; 
but in Dytiscus marginalis, &c. the reverse of this takes 
place : the female, if you reckon the bipartite half-con- 
cealed anal segment as one, having seven ventral seg- 
ments, and the male only six. She has also eight dorsal, 
and the male seven. — In the ant tribes [Formica L.), the 
little vertical scale, at the base of the abdomen in one 
description of them, or the double knot in another, is 
less in the male than in the female. In a very singular 
male insect belonging to the Vespidce, and related to Sy- 
nagris, (which I purchased from the late Mr. Drury's ca- 
binet, ) the second ventral segment sends forth from its 
disk two remarkable parallel very acute and rather long 
spines. The same sex of Chclostoma maxillosa has like- 
wise on the same segment a concave elevation, opposite 
to which on the fifth is a cavity which receives it, when 
the animal rolls itself up to take its repose b . In another 
species, C. Campanularum, the segment in question has 
only a tubercle c . 

On the second segment of the abdomen of some spe- 

a De Geer v. 151 — . 

b Mon. Ap. Angl. i. 177- 1. ix. Apis **. e. 2. y.f. 11. a, d. 

< Ibid.f. 13. a. 

z 2 



340 STATES OF INSECTS. 

cimens, probably males, of the remarkable African ge- 
nus Pneumora before alluded to % there are thirteen lit- 
tle elevated ridges, placed rather obliquely in an oblique 
series; and gradually", though slightly, diminishing in 
size towards the belly : on their upper side they are flat, 
forming nearly a horizontal ledge, but on the lower they 
slope to the abdomen. The posterior thigh in its natu- 
ral position covers the three first of them, and, if moved 
downwards, would strike them all b . I conjecture, there- 
fore, that these are the animal's instruments of sound, 
imitating the harp or violin rather than the drum ; and 
that the thigh acts the part of the hand or bow. The 
abdomen of these insects being blown out like a bladder, 
and almost empty c , must emit a considerable sound when 
the thigh of the animal passes briskly over these ridges ; 
and their different length would produce a modulation 
in the sound. When struck with a pin, they emit a gra- 
ting noise. 

In Sta-phylinus splende?is, the penultimate ventral seg- 
ment is very deeply cleft, and the antepenultimate emar- 
ginate in one sex, and intire in the other. In S. lamina- 
tus, an allied species, the penultimate segment is cleft, 
less deeply, however; but the antepenultimate is very 
short and intire; while the fourth is extremely long, and 
rounded at the margin, appearing as if it was only an 
elevated part of the last-mentioned segment ; for which 
it was mistaken by Gravenhorst d , while it is of the usual 
form in the other sex. 

a See above, Vol. II. 395. 

b Plate XXIX. Fig. 13. Stoll. Spectres, &c. t. xxv.f. 99. 

c Sparrman". Voyage, i. 312 — . 

d Coleopt. Micropt. 1G. 



STATES OF INSECTS. 341 

The extremity of. the abdomen, or its anal segments 
and organs famish a variety of sexual characters. Some- 
times the last dorsal segment is emarginate in the male, 
and not in the female ; as in Megachile ligniseca, one of 
the leaf-cutter bees, Cimex hcemor?7ioidalis, &c. a At 
other times little lateral teeth are added to this notch, as 
in another of the same tribe, M. Willughbiella b . Again, 
in other males, both the ventral and dorsal anal segment 
are armed each with a pair of teeth or mucros, as in 
Chelostoma maxillosa c . In Anthidium manicaium, an- 
other bee, the anus terminates in five spines d . In Cceli- 
oxys conica of the same tribe, in which this part in the 
female is very acute, that of the male is armed with six 
points e . In that singular Neuropterous genus Panorpa, 
while the abdomen of the female is of the ordinary form, 
with a pair of biarticulate palpiform organs attached to the 
last retractile joint, or ovipositor, that of the male termi- 
nates in a jointed tail, not unlike a scorpion's, at the end 
of which is an incrassated joint armed with a forceps f . In 
the common earwig {JForficula auricularia) the two sexes 
differ considerably in their anal forceps: in one it is armed 
with internal teeth at the base, and suddenly dilated, above 
which dilatation it is bent like a bow : in the other it is 
smaller, without teeth, grows gradually narrower, is 
very minutely crenulate from the base to the end, and is 
straight, except at the very summit, where it curves in- 
wards. Misled by these and similar differences, Mr. Mar- 

a Mon. Ap. Angl. i. t, viii./. 25. De Geer iii. 255. t. xiv./. 8. 

b Mon. Ap. Angl. i. t. viii./. 24. c Ibid. t. ix. Apis xx. c. 2. y.f. 12. 

^Ibid. Apis **. c. 2. fi.f. 11. 

" Ibid. t. vii.Apis**. c. 1. *./ 11, 12. $ . 13, 14. $. 

{ Plate XV. Fig. 12. De Geer ii. I. xxiv. /. 9, 10. $ . t. xxv. 



34-2 STATES OF INSECTS. 

sham has considered them (the sexes both of F. auncu- 
laria and F. minor) as distinct species. 

The tail of some species of the genus Ephemera is fur- 
nished with three long, jointed, hairy bristles. We learn 
from Reaumur with respect to one, that though in the 
female these are all equal in length, yet in the male there 
is only a rudiment of the third. On the belly near the 
anus these males have four fleshy appendages, the poste- 
rior ones setaceous and long, and the anterior pair fili- 
form and shorter. They are supposed to represent the 
anal forceps of other insects a . In Ephemera vulgata, 
described by De Geer, both sexes have three bristles, 
but those of the male are the longest ; and he describes 
the forceps as consisting of only a pair of jointed pieces, 
forming a bow not unlike the forceps of an earwig b . 

v. All the differences I have hitherto noticed between 
the sexes of insects occur in their bodily structure ; but 
there are others of a somewhat higher description ob- 
servable in their character. You may smile at the idea 
of character in beings so minute; but if you recollect what 
I formerly related to you when treating upon the socie- 
ties of insects, you will allow that something of this kind 
does take place amongst them. In general the males are 
more fatted for locomotion and more locomotive; and 
the females, on the contrary, are necessarily more sta- 
tionary. And this for an obvious reason : — the law is, 
that the male shall seek the female, and therefore he is 
peculiarly gifted for this purpose, both in his organs of 
sensation and motion : while his partner in many cases 
has very simple antennae, he has very complex ones; and 

* Reaum. vi. 494. t. xliv./ 3—11. * De Geer ii. t. xvii./. 5—7- 



STATES OP INSECTS. 34-3 

while she has either no wings or only rudiments of them, 
he is amply provided with them. Again : amongst the 
insects that suck the blood of man or beast, such as the 
gnat (Culex) or horse-flies (Tabanida), it is the female 
alone that is bloodthirsty, the males contenting them- 
selves with the nectar of flowers a . But the difference of 
character in the sexes is most conspicuous, at least it has 
been more noticed, in those that live in societies, and is 
quite the reverse of what takes place in the human spe- 
cies. While the females and workers (which are now 
generally considered as sterile females, in which the ova- 
ries are not developed) are laborious and active, diligent 
and skilful, wise and prudent, courageous and warlike; — 
the males, on the contrary, take no part in promoting the 
common weal, except merely a sexual one. Though till 
a certain period they are supported at the expense of the 
community, they take no part in its labours, either in 
collecting and forming the public stores, or in feeding 
and attending the young. They are idle, cowardly, and 
inactive ; have neither art nor skill of any kind, and 
are unprovided with the usual offensive weapons of theii 
species. These observations in their full force apply par- 
ticularly to the hive-bee, and partially to the other social 
insects; amongst which, if you consult my former com- 
munications, there are some exceptions to this slothful 
character in the males b . 

II. Age. There is less diversity in the duration of the 
lives of insects in their perfect than in their larva or pupa 

a N. Diet. d'Hisf. Nat. xxxii. 44;?. 
"See above, Vol. II. 110, 118. 



314 STATES OF INSECTS. 

state. Some, like several species of Ephemera', live only 
a few hours ; some never even see the sun a : others, as 
flies, moths, and butterflies, and indeed the majority of 
insects, a few days or weeks ; and a comparatively small 
number, such as some of the larger Coleoptera, Ottho- 
ptera, &c, six, nine, twelve, or fifteen months — a period 
beyond which the life of perfect insects rarely extends. 
Some, however, certainly enjoy a longer existence in the 
perfect state. Mr. Baker kept one of the darkling beetles 
(Blaps Mortisaga) alive under a glass upwards of three 
years. The rose-beetle (Cetonia aurata), Rosel informs 
us he fed with fruit and moist white bread for as long a 
period 5 . Esper kept our most common water-beetle 
(Dytiseus marginalis) in water in a large glass vessel, 
feeding it with meat, for three years and a half c . With 
regard to the Arachnida, from the very slow growth of 
Scorpio europtzus, Rosel suspects that it must live two 
or three years ; and Audebert is stated to have kept a 
spider for several d . In this respect insects follow a law 
very different from that which obtains amongst verte-> 
brate animals. In these the duration of their life is in 
proportion to the term of their growth : those which at- 
tain to maturity the latest, in almost every case living the 
longest. In insects, on the contrary, we often meet with 
the very reverse of this rule. Thus the larva of the great 



a Vol. 1. 283. h II. i. 6. 

c Clairville Ent. Helvet. ii. 214 — . I have seen it asserted in some 
popular work on Natural History, (the title of which I do not recol- 
lect,) that Mantis religiosa has been known to live ten years ; and a 
flea, when fed and taken care of, six. But this is so contrary to expe- 
rience in other cases, that the statement seems quite incredible. 

d Rosel III. 379. N. Diet. d'Hist. Nat. ii. 285. 



States of insects. 345 

goat-moth (Cossus ligniperdcty is three years, that of the 
cabbage-butterfly (Pieris Brassicce) not three months, in 
attaining maturity ; yet the perfect insects live equally 
long. Melolontha vulgaris, which in its first state lives 
four years, as a beetle lives only eight or ten days a . 
And some Ephemera, whose larvae have been two years 
in acquiring their full size, live only an hour ; while the 
flesh-fly, whose larva has attained to maturity in three or 
four days, will exist several weeks. 

There is yet another anomaly in the duration of the 
life of perfect insects. This is not, as in larger animals, 
a fixed period liable to be shortened only by accident or 
disease, and incapable of being prolonged ; but an inde- 
terminate one, whose duration is dependent on the ear- 
lier or later fulfilment of a particular animal function — 
that of propagation. The general law is, that a few days, 
or at most weeks, after the union of the sexes, both pe- 
rish, the female having first deposited her eggs. If, 
therefore, this union takes place immediately after the 
disclosure of the insect from the pupa, their existence in 
the perfect state will not exceed a few days or weeks, or 
in some cases hours, as in that of the Ephemera, and like- 
wise of the Phalcena Attaci L. &c, which fall down dead 
immediately after oviposition b . But if by any means it 
be put off or prevented, their life may be protracted to 
three or four times that period. Gleditsch asserts, that 
by keeping apart the sexes of a grasshopper, their lives 
were prolonged to eight or nine weeks, instead of two or 
three, their ordinary length; and under similar circum- 
stances Ephemera, which usually perish in a day, have 

a Dumeril Traile Element, ii. 87- n. 683. b Be Geer ii. '2§8. 



346 STATES OF INSECTS. 

been kept alive seven or eight. It is in consequence of 
this very curious fact, which has not received from phy- 
siologists the attention that it merits, that many butter- 
flies and other insects, which, when excluded from the 
pupa in summer, perish in less than a month, live 
through the winter, if excluded late in the autumn, and 
the union of the sexes does not ensue. It is probable 
that the great age to which Baker's Blaps, Rosel's Ceto- 
nia, and Esper's Dytiscus attained, was owing to their 
being virgins when taken, and subsequently kept from 
any sexual intercourse. A parallel case happens in the 
vegetable kingdom : — if annual plants are kept from seed- 
ing, they will become biennial ; as, likewise, if they are 
sown too late in the year to produce seeds. 

In the case, however, of the earlier or later exclusion 
of the imago, another agent has probably some influ- 
ence. Buffon found that, other circumstances being alike, 
the silkworm-moths placed in a northern, lived longer 
than those exposed to a southern aspect : whence it ap- 
pears that the stimulus of heat shortens the lives of in- 
sects, and consequently that cold tends to lengthen 
them. 

It must be observed too, that as the death of the fe- 
male insect does not take place until all the eggs are ex- 
cluded, the term of her life, though usually short in the 
majority of species, which lay their whole number at 
once, is proportion ably long in those which, like the 
queen-bee, have a longer period assigned them for this 
important office. Huber affirms, that he had certain 
proofs that she was engaged for two years in laying eggs, 
all impregnated by a single sexual union a ; and in the 
a Huber i. 106. 



STATES OK INSECTS. 347 

females of most insects that live in society, several months 
are required to mature the last eggs that are in the 
ovary. There is one tribe of insects, however, the fe- 
males of which are affirmed to survive this operation : 
I mean Dorthesia Bosc ; after which they even moult, 
thouovh not so often as before a . 

I formerly related to you the singular fact, that the 
drones in a beehive at a certain period are without mercy 
slaughtered by the workers b . A fact the reverse of this 
is recorded by Morier with respect to the locusts : he 
affirms that the female, when she has done laying her 
eggs, is surrounded and killed by the males. He saj^s 
that he never himself witnessed this extraordinary cir- 
cumstance ; but that he heard it from such authority that 
he gave full credit to it c . It is a fact, however, that 
seems to require further evidence to entitle it to such cre- 
dit. These are instances in which, by a law of nature, 
the life of these insects is shortened by violence. It does 
not appear to have been ascertained how long those 
drones live that, under particular circumstances, as stated 
in a former letter d , are exempted from the usual slaugh- 
ter. 

I am, &c. 

a N. Diet. d'Hist. Nat. ix. 553. " Vol. II. 173—. 

c Morier's Second Journey through Persia, 1 00. 
d Vol. II. 175. 



LETTER XXXIII. 



EXTERNAL ANATOMY OF INSECTS. 

TERMS, AND THEIR DEFINITION. 

HAVING shown you our little animals in every state, 
and traced their progress from the egg to the perfect 
insect, I must next give you some account of their struc- 
ture and anatomy. And under this head I shall intro- 
duce you to a microcosm of wonders, in which the hand 
of an Almighty workman is singularly conspicuous. 
One would at first think that the giant bulk of the ele- 
phant, rhinoceros, or hippopotamus, must include a ma- 
chine far more complicated, a skeleton more multifarious 
in its composition — covered by muscles infinitely more 
numerous — instinct with a nervous system infinitely more 
ramified — with a greater variety of organs and vascular 
systems in play, than an animal that would scarcely coun- 
terpoise a ten-millionth portion of it. Yet the reverse of 
this is the fact ; for the Creator, the more to illustrate 
his wisdom, power, and skill, has decreed that the mi- 
nute animals whose history we are recording, shall be 
much more complex in all the above respects than -these 
mighty monarchs of the forest and the flood. Of this 
in the present and subsequent letters you will find re- 



EXTERNAL ANATOMY OF INSECTS. 349 

peated and scarcely credible instances, which in every 
rightly constituted mind are calculated to excite, in an 
extraordinary degree, those sensations of reverence and 
love for the Invisible Author of these wonders, and 
that faith and trust in his Power and Providence, which 
an attentive survey of the works of Creation has a natu- 
ral tendency to produce. And you will not only be 
struck by this circumstance, but equally by the infinite 
variations in the structure that will present themselves to 
your notice ; and that not sudden and per saltus, but by 
approaches made in the most gradual manner from one 
form to another. And all along, where the uses of any 
particular organ or part have been ascertained, if you 
consider its structure with due attention, you will find in 
it the nicest adaptation of means to an end : a circum- 
stance this, which proves most triumphantly, that the 
Power who hnmediately gave being to all the animal 
forms, was neither a blind unconscious power, resulting 
from a certain order of things, as some philosophists love 
to speak a ; nor a formative appetency in the animals 
themselves, produced by their wants, habits, and local 
circumstances, and giving birth, in the lapse of ages, to 
all the animal forms that now people our globe b ; but a 
Power altogether distinct from and above nature, and its 
Almighty Author . 

a Lamarck Hist. Nat. des Anim. sans Vertcbr. i. 311, 214. 

b Ibid. 162. Compare the Systcme des Anim. sans Vertebr. of the 
same author, p. 12 — . 

c The doctrine of Epicurus — that the Deity concerns not himself 
with the affairs of the world or its inhabitants, which, as Cicero has 
judiciously observed (De Nat. Deor. 1. 1. ad calcem), while it ac- 
knowledges a God in ivords, denies him in reality ; has furnished 
the original stock upon which most of these bitter fruits of modern 



350 EXTERNAL ANATOMY OF INSECTS. 

I trust that what I have here advanced will excite your 
attention to the subject I am now to enter upon ; and I 
flatter myself, that although at first sight it may promise 
nothing more than a dry and tedious detail of parts and 
organs, you will find it not without its peculiar interest 
and attraction. 

This department of the science — the Anatomy of In- 
sects — may still be regarded as in its infancy ; and consi- 

infidelity are grafted. Nature, in the eyes of a large proportion of the 
enemies of Revelation, occupies the place and does the work of its 
Great Author. Thus Hume, when he writes against miracles, ap- 
pears to think that the Deity has delegated some or all of his powers 
to nature, and will not interfere with that trust. Essays, ii. 75 — . 
And to name no more, Lamarck, treading in some measure in the 
steps of Robinet (who supposes that all the links of the animal king- 
dom, in which nature gradually ascends from low to high, were ex- 
periments in her progress towards her great and ultimate aim — the 
formation of man. Barclay On Organization, &c. 263), thus states his 
opinion : " La nature, dans toutes ses operations, ne pouvant pro- 
ceder que graduellement, n'a pu produire tous les animaux a-la-fois : 
elle n'a d'abord forme que les plus simples; et passant de ceux-ci 
jusques aux plus composes, elle a etabli successivement en eux dif- 
ferens systemes d'organes particuliers, les a multiplies, en a augmente 
de plus en plus l'energie, et, les cumulant dans les plus parfaits, elle 
a fait exister tous les animaux connus avec l'organisation et les fa- 
cultes que nous leur observons." (Anim. sans Vertebr. i. 123.) Thus 
denying to the Creator the glory of forming those works of cre- 
ation, the animal and vegetable kingdom (for he assigns to both the 
same origin, Ibid. 83), in which his glorious attributes are most con- 
spicuously manifested; and ascribing them to nature, or a certain 
order of things, as he defines it (214)— a blind power, that operates 
necessarily (311); which he admits, however, to be the pi'oduct of 
the will of the Supreme Being (216). It is remarkable, that in his 
earlier works, in which he broaches a similar opinion, we find no 
mention of a Supreme Being. (See his Systeme des Animaux sans Ver- 
tebres, Discours d'Ouverture.) Thus we may say that, like his fore- 
runner Epicurus, Re tollit, dum oratione relinquit Beum. But though 
he ascribes all to nature ; yet as the immediate cause of all the ani- 



EXTERNAL ANATOMY OF INSECTS. 351 

dering the almost insuperable difficulties which, from the 
minuteness of the objects, oppose themselves to the skill 
and instruments of the entomological anatomist, we can 
scarcely hope that it will ever attain to that certainty and 
perfection to which, as far as the larger animals are con- 
cerned, anatomy has arrived. Yet infinitely more has 
been accomplished than might have been expected, and 
new accessions of light are daily thrown upon it. When 

mal forms, he refers to the local circumstances, wants, and habits of 
individual animals themselves ; these he regards as the modifiers of 
their organization and structure (102). To show the absurd nonplus 
to which this his favourite theory has reduced him, it will only be ne- 
cessary to mention the individual instances which in different works 
he adduces to exemplify it. In his Systeme, he supposes that the 
web-footed birds {Anseres) acquired their natatory feet by frequently 
separating their toes as far as possible from each other in their efforts 
to swim. Thus the skin that unites these toes at their base con- 
tracted a habit of stretching itself; and thus in time the web-foot of 
the duck and the goose were produced. The waders {Grallce), 
which, in order to procure their food, must stand in the water, but 
do not love to swim, from their constant efforts to keep their bodies 
from submersion, were in the habit of always stretching their legs 
with this view, till they grew long enough to save them the trou- 
ble ! ! ! (13 — ). How the poor birds escaped drowning before they 
had got their web feet and long legs, the author does not inform us. 
In another work, which I have not now by me, I recollect he attri- 
butes the long neck of the camelopard to its efforts to reach the 
boughs of the mimosa, which, after the lapse of a few thousand years, 
it at length accomplished ! ! ! In his last work, he selects as an ex- 
ample one of the Molluscce, which, as it moved along, felt an incli- 
nation to explore by means of touch the bodies in its path : for this 
purpose it caused the nervous and other fluids to move in masses 
successively to certain points of its head, and thus in process of 
time it acquired its horns or tentacula ! ! Aram, sans Vertebr. i. 188. 
It is grievous that this eminent zoologist, who in other respects 
stands at the head of his science, should patronize notions so con- 
fessedly absurd and childish. 



352 EXTERNAL ANATOMY OF INSECTS. 

we consider what has been done by Malpiglii, Leeuwen- 
hoeck, and especially Swammerdam, we admire the pa- 
tience, assiduity, and love of science, that enabled them, in 
spite of what seemed insurmountable obstacles, to ascer- 
tain, the first with respect to the silk-worm, and the latter 
in numerous instances, the internal organization of these 
minute creatures, as well as their external structure. 
Reaumur, and his disciple De Geer, extending their re- 
searches, have also contributed copiously to our know- 
ledge in this branch of our science. 

But in this field no one has laboured so inclefatigably 
and with so much success as the celebrated Lyonnet ; and 
though his attention was confined to one object — the ca- 
terpillar of the goat-moth [Cossus ligniperda F.), — every 
one who studies his immortal work must admire the 
patient and skilful hand, the lyncean eye, and keen in- 
tellect, that discovered, denuded, and traced every organ, 
muscle, and fibre of that animal. Much is it to be re- 
gretted that his proposed works on the pupa and imago 
of the same insect, which, he informs us, were far ad- 
vanced 11 , were never finished and given to the world. 
Our regret, however, is in some degree diminished by 
the elaborate work of M. Herold on the butterfly of the 
cabbage [Pieris Brassicce), before eulogized b ; in which 
he has done much to supply this desideratum. 

In more modern times, besides Herold, MM. Latreille, 
Illiger, Marcelle de Serres, Savigny, Ramdohr, Trevi- 

a Lyonnet Traite, &c. Pref. xxii. Want of due encouragement, 
it is to be feared, caused the abortion of these valuable treatises. 
The MSS. are, I believe, still in existence. It would probably an- 
swer now to publish them. 

b See above, p. 52 — . 



EXTERNAL ANATOMY OF INSECTS. 353 

raniiSj Sprengel, Audoin, Chabrier, and, above all, M. 
Cuvier in his celebrated Lectures on Comparative Ana* 
tomy, have considerably extended the boundaries of our 
knowledge in this department : and much of what I have 
to say to you in my letters on this subject, will be derived 
from these respectable sources. In the exterior anatomy 
of insects, I flatter myself that I shall be enabled to make 
some material additions to the discoveries of my prede- 
cessors ; though few have occurred to me with respect to 
their internal organization. 

In treating of the anatomy of the vertebrate animals^ 
it is usual, I believe, to consider, first, the skeleton and 
its integuments, whether of skin or muscle, and their 
accessories ; and afterwards the organs of the different 
vital functions and of the senses. But in considering 
the anatomy of Insects, the difference before stated a , ob- 
servable between them and the sub-kingdom just men- 
tioned, as to their structure, renders it advisable to divide 
this subject into two parts — the first treating of their 
external anatomy, and the second of their internal. — 
I shall begin by drawing up for you a Table of the No- 
menclature of the parts of their external crust ; its ap- 
pendages and processes b , external or internal, accompa- 
nied by definitions of them ; and followed by such obser- 
vations respecting them as the subject may seem to re- 
quire for its more full elucidation. 

Anatomists have divided the human skeleton into three 



a See above, p. 43 — . 

b There are certain processes which are a continuation of the in- 
ternal surface of the crust ; and serve, as well as the rest of it, for 
points of attachment to the muscles : these, though completely in- 
ternal, must be considered as parts of the external skeleton. 

VOL. III. 2 A 



3<H< EXTERNAL ANATOMY OF INSECTS. 

greater sections — the Head, the Trunk, and the Limbs. 
That of insects, likewise, is resolvable into three primary- 
sections, but without including the limbs (which, as be- 
ing appendages, and therefore secondary, had best be 
considered under the section of which they form a part), 
for the abdomen in insects, as well as the rest of the body, 
being covered with a crust, and forming a distinct part, 
may be properly regarded as a primary section. And in 
fact these three parts may be received as primary under 
another view — the head, as containing the principal or- 
gans of sensation ; the trunk, as containing those of mo- 
tion; and the abdomen, as containing those of generation* ■. 
Under each of these primary sections, I shall consider its 
respective organs, members, and parts. 

You are not to expect to find every part included in 
the following Table in every insect; since it has been my 
aim to introduce into it, the most remarkable of those 
that are peculiar to particular tribes, genera, &c. With 
respect to these, I shall generally refer you to the indivi- 
duals in which they may be found. 



DEFINITIONS. 

Corpus (the Body). The whole crust of the insect; 
consisting of the Exoderma or external covering, and 
the Esoderma or internal cuticle that lines it b . It is 
divided into three primary parts, or sections — Caput, 
Truncus, Abdomen. 

a See above, p. 28 — . 

h The crust which covers the body of insects is lined internally 
with a kind of iibrous cuticle. Query, Whether in any degree ana- 
logous to the Periosteum of Vertebrate animals ? 



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EXTERNAL ANATOMY OF INSECTS. 355 

I. CAPUT (The Head). 
The Head is the anterior section, of the body; con- 
sisting of a kind of box without suture or segment, which 
receives the organs of sensation and manducation. It 
includes the Os, Fades, Subfacies, and Collum. 

i. Os (the Mouth). That part of the head which re- 
ceives and prepares the food for passing into the 
stomach. It includes the Trophi a . 

1. Trophi (the Trophi). The different instruments or 
organs contained in the mouth, or closing it, and 
employed in manducation or deglutition. They in- 
clude the Labrum, Labium, Mandibular, Maxilla', 
Lingua, and Pharynx. 

A Labrum (the Upper-lip). A usually moveable or- 
gan ; which, terminating the face anteriorly, covers 
the mouth from above, and is situate between the 
Mandibular h . It includes the Appendicula. 

a Appendicula (the Appendicle). A small piece some- 
times appended to the upper-lip c . Ex. Halictus ? 
Walck. {Melitta **. b. K.) 

B Labium (the Under-lip). A moveable organ, often 
biarticulate, which terminating the surface ante- 
riorly, covers the mouth from beneath, and is situ- 
ate between the Maxilla: d . It includes the Men- 
tum, and Palpi Labiales. 

a Mentum (the Chin). The lower joint of the Labium, 

a We employ this term instead of Instrumenla Cibaria ¥. 3 to avoid- 
circumlocution. 

*> Plates VI. VII. &c. a', and XXVI. Fig. 30-33. 
e Ibid. Fig. 30. Mon. Ap. Angl. i. 139. Melitta **. b. t. ii./. 4 S 5. 
•' Plates VI. VII. &c. and XXVI. Fia. 23—29. b'. 
2 A 2 



S5G EXTERNAL ANATOMY OF INSECTS. 

where it is jointed ; in other cases its base. It is 
usually seated between the base of the Maxil- 
la*. 

b Palpi Labiales (the Labial Feelers). Two jointed 
sensiferous organs, the use of which is not clearly 
ascertained, which emerge, one on each side, from 
the Labium, mostly near its summit b . 

C Mandibul^: (the Uppe7-jaws). Two transverse late- 
ral organs, in most insects used for manducation ; 
generally corneous, moving horizontally, and clos- 
ing the mouth above, under the Labium c . They 
include the Prostheca, Dentes, and Mola. 

a Prostheca (the Prostheca). A subcartilaginous pro- 
cess attached to the inner side, near the base, of the 
Mandibular of some Staphyli?iidce d . Ex. Ocypus 
similis K., Creophilus maxillosus K., &c. 

b Dentes (the Teeth). The terminating points of the 
Mandibida?. They include the Incisores, Laniarii, 
and Molares e . 

A Incisores (the Cutting-teeth). Teeth somewhat 
wedge-shaped, externally convex and internally 

3 Plates VI. and VII. a", and XXVI. Fig. 34, 35. 

The part in this work regarded as the mentum, does not in all 
cases accord with what MM. Latreille, Savigny, &c. have regarded 
as entitled to that denomination. Thus in Hymenopiera, their 
Mentum is what we term the Labium, while our Mentum is the 
small piece upon which that part sits (Plate VII. Fig. 3. a"). This 
is called the Fulcrum in Mon. Ap. Angl. (See i. Explan. of the 
Plates.) Our Mentum may generally be known by its situation be- 
tween the hinges and base of the Maxillae. 

b Plates VI., VII., and XXVI. b". c Ibid. 

d Plate XIII. Fig. 7. c". 

e Marcel de Serres Comparaison des Organes de la Mastication de& 
Orthopteres. 7- Ann. du Mus. 11. 



EXTERNAL ANATOMY OF INSECTS. 357 

concave a . Ex. Gryllotaljpa Latr., Gryllus Latr. 
{Acheta R), &c. &c. 

B Laniarii (the Canine-teeth). Very sharp and usu- 
ally long conical teeth b . Ex. Forficula L., Man- 
tis L., Libellula L. 

C Molares (the Grinding-teeth). Teeth that terminate 
in a broad uneven surface, fit for grinding the food c . 
Ex. the herbivorous OrtJwptera. 

c Mola (the Mola). A broad, flat, subrotund space, 
transversely grooved or furrowed, observable on the 
inner side of some mandibles that have no grind- 
ing-teeth at their apex d . Ex. Euchlora MacLeay, 
Anoplognathus Leach, Larva of Lucanus e . 

D Maxilla (the Under-jmsos). Two organs moving 
sub horizontally, fixed on each side at the base of 
the Labium, and often parallel with it — which in 
masticating insects seem primarily designed to hold 
the food f . They include the Cardo, Stipes, Lobi, 
and Palpi maxillares. 

a Cardo (the Hinge). A small, transverse, usually 
triangular, corneous piece, upon which the Maxilla 
commonly sits s . 

b Stipes (the Stalk). The corneous base of the Max- 
illa, below the Palpus h . 

c Lobi (the Lobes). The parts of the Maxilla above 
the Palpus '. They include the Lobus superior, the 
Lobus inferior, and the Ungues. 

a Plate VI. Fig. 6. c', a'", and XIII. Fig. 5, a'". 

b Plate VI. Fig. 12. b'". and XIII. Fig. 5. b'". 

c Plate XXVI. Fig. 16. c'". li Ibid. Fig. 20. d"\ 

e Cuv. Anat. Comp. iii. 322—. 

f Plates VI. VII. d'- and XXVI. Fig. 9—15. 

s Ibid, e", h Ibid. f". '' Ibid, and XXVI. Fig. 13-15. 



358 EXTERNAL ANATOMY OF INSECTS. 

A Lobus Superior (the Upper-lobe). The outer lobe 
of the Maxilla, incumbent on the inner one. In 
the Predaceous Beetles this lobe is Inarticulate and 
palpiform a ; and in Staphylimis olens, &c. it also 
consists of two joints b . It is called the Galea by 
Fabricius, in Orthoptera, &c. c 

B Lobus Inferior (the Lower-lobe). The inner lobe 
of the Maxilla, covered by the outer one d . 

C Ungues (the Claws). One or more corneous sharp 
claws which arm the lobes of the Maxilla e . In the 
Predaceous Beetles there is only one terminating 
the lower lobe, with which, in Cicindela, it articu- 
lates ; in the Orthoptera and Libellidina there are 
several. 

d Palpi Maxillares (the Maxillary Feelers). Two 
jointed sensiferous organs, the use of which is not 
clearly ascertained, emerging from an exterior la- 
teral sinus of the Maxilla f . 

E Lingua (the Tongue). The organ situated within 
the Labium or emerging from it, by which insects 
in many cases collect their food and pass it down 
to the Pharynx, situated at its roots above. It va- 
ries considerably in different orders and tribes. In 
the Orthoptera, Libellidina, &c. it is linguiform, 
and quite distinct from the Labium S; it appears 
also distinct in the lamellicorn beetles, &c. h In many 

a Plate VI. Fig. 3. d'". t p LATE XXVI. Fig. 11. d'". 

c Plate VI. Fig. 6, 12. d'". 
<> Ibid. Fig. 3, 6, 12. and XXVI. Fig. 9, 10. e'". 
c Ibid. VI. Fig. 3, 12. f". 

f Plates VI. VII. h". XIII. Fig. 1—4, 8. h". and XXVI. 
Fig. 1—8. ' Plate VI. Fig. 6, 12. e'. 

" Plate XXVI. Fig. 26, 29. e'. 



EXTERNAL ANATOMY OF INSECTS. 359 

Hymenopiera it emerges from the Labium, and is 
fitted to collect liquids and pass them downwards a . 
In Formica it appears to be retractile b . In a con- 
siderable proportion of insects it seems connate 
with the Labium, and forming its inner surface? 
According to circumstances it might perhaps be 
denominated Lingua or Ligula. It includes the Pa- 
raglosscB. 

a ParaglosSjE (the Paraglossa). Lateral and often 
membranous processes observable on each side of 
the tongue in some Hymenoptera, &c. c 

F Pharynx (the Pharynx). The opening into the gul- 
let d . It includes the Epipharynx and Hypopha- 
rynx. 

a Epipharynx (the Epipharynx). A small valve under 
the Labrum, that in many Hymenoptera closes the 
Pharynx, and is an appendage of its upper mar- 
gin 6 . 

b Hypopharynx (the Hypopharynx). An appendage 



a Plate VII. Fig. 2, 3, e'. — What is here called the Lingua in 
Hymenoptera has been usually regarded as the Labium ; but surely that 
organ which collects, and as it were laps the honey, and passes it 
down to the Pharynx, is properly to be considered as the tongue. 
The Labium itself appears to be represented by what has been called 
the Mentum, and the true Mentum, as was lately observed, is at the 
base of the part last mentioned, in the usual situation of that piece. 
This, though long since noticed (Kirby Mon. Ap. Angl. i. ] Oo— ), has 
not been much attended to by modern entomologists. 

b Huber Fourmis, 4 — . 

c Plate VII. Fig. 2, 3. and XXVI. Fig. 28. i". 

J Plate VII. Fig. 14. P. 

e Ibid. Fig. 2. k". This is M. Savigny's name for this part. It 
has also been called Epiglossa. Latreille Organisation Exterieure des 
Insecics. 185. 



S60 EXTERNAL ANATOMY OF INSECTS. 

of the lower margin of the Pharynx, observable in 
Eucera F. a 

The seven organs of the mouth above defined, viz. the 
Labrum, Labium, the two Mandibular, the two Maxillae, 
and the Lingua, constitute what may be denominated a 
perfect mouth, peculiar to those insects that masticate their 
food b . In those that take it by suction, the Trophi, to 
adapt them for that purpose, assume a variety of forms, 
and should be distinguished by as many appellations. In 
almost every case, however, the rudiments or representa- 
tives of the above organs have been detected by the elabo- 
rate researches of that learned, and able zoologist, M. Sa- 
vigny c . I shall next subjoin definitions of the principal 
kinds of suctorious mouths. 

2. Promuscis (the Promuscis). The oral instrument of 
Hemiptera, in which the ordinary Trophi axe re- 
placed d by a jointed sheath, covered above at the 
base by the Labrum, without Lobelia (Liplets) at 
the end, and containing four long capillary lancets, 
and a short tongue e . It includes the Vagina, and 
Scalptella. 



a Vide Savigny Mem. sur les Anim. sans Vertebr. I. i. 12 — . 

b The majority of Hymenopterous insects, though they have the 
ordinary Tropin, are not masticators, using their mandibula only for 
purposes connected with their economy. 

c See his Memoires sur les Animaux sans Vertebres, I. i. 

d I have used this word here and on a former occasion (see above, 
p. 29), perhaps not with strict propriety, in the sense of the French 
word remplacer, for which we seem to have no single corresponding 
word in our language. 

e Plate VI. Fig. 7—9. 



EXTERNAL ANATOMY OF INSECTS. 361 

A Vagina (the Vagina). The jointed sheath of the 
Promuscis, representing the Labium in a perfect 
mouth a . 

B Scalpella (the Lancets). Four pieces adapted for 
perforating the food of the insect, which when 
united form a tube for suction. The upper pair 
represent the Mandibulaj b , and the lower the Max- 
illa? c . 

3. Proboscis (the Proboscis). The oral instrument of 
Diptera, in which the ordinary Trophi are replaced 
by an exarticulate sheath, terminated by Labella, 
and containing one or more lancets covered by a 
valve d . It includes the Theca, and Haustellum. 

A Theca (the Theca). The sheath or case of the Pro- 
boscis, representing the Labium in a perfect mouth e . 
It includes the Basis, and Lobelia. 

a Basis (the Base). The whole lower part of the Theca, 
from the mouth of the insect as far as the Lobelia, 
probably to be regarded as representing the Men- 
turn ? 

b Labella (the Liplets). A pair of tumid lobes, often 
corrugated and capable of tension and relaxation, 
which terminate the Theca, and perhaps represent 
the termination of the Labium s ? 

B Haustellum (the Haustellum). The instrument of 
suction contained in the Theca h . It includes the 
Valvula, Cultelli, and Scalpella. 

a Plate VI. Fig. 7, 9. b'. b Ibid. c'. c Ibid. d'. 

d Ibid. VII. Fig. 5, 6. e Ibid. b'. f Ibid. Fig. 6. b. 

8 Ibid. a. The Labella have been usually thought confined, or 
nearly so, to the genus Miisca L. ; but they may be traced in all ge- 
nuine Diptera, i. e. excluding Hippobosca L. 

h Plate VII. Fig. 5. a', c', d'. 



362 EXTERNAL ANATOMY OF INSECTS. 

a Valvula (the Valvule). A corneous piece which 
covers the instruments of suction above, represent- 
ing the Labrum in a perfect mouth a . 

b Cultelli (the Knives). The upper pair of the in- 
struments of suction, which probably make the first 
incision in the food of the insect; they represent 
the Mandibida? of the perfect mouth b . 

c Scalpella (the Lancets). A pair of instruments, 
usually more slender than the Cultelli, which pro- 
bably enter the veins or sap-vessels, and together 
with them form a tube for suction c . 

4. Antlia (the Antlia). The oral instrument of Lepi- 

doptera, in which the ordinary Tropin are replaced 
by a spiral, bipartite, tubular machine for suction, 
with its appendages d . It includes the Solenaria, 
and Fistida. 

A Solenaria (the Solenaria). The two lateral subcy- 
lindrical air-tubes of the Antlia e . 

B Fistula (the Fistula). The intermediate subqua- 
drangular pipe, formed by the union of the two 
branches of the Antlia, which conveys the nectar 
to the Pharynx f . These two branches represent 
the Maxilla of the perfect mouth. — N. B. M. Sa- 
vigny discovered the rudiments of the remaining 
Tropin in this hind of mouth s . 

5. Rostrulum (the Hoslridum). The oral instrument 



; < Plate VII. Fig. 5, G. a'. b Ibid. c'. 

c Ibid. d'. It has not yet been satisfactorily ascertained, whether 
all the ordinary Trophi are represented in every Dipterous mouth, 
the number of the lancets seeming in some cases to vary. 

d Plate VI. Fig. 13. e Ibid. a. f Ibid. b. 

p Ibid. Labrum a'; Mandibular c'; Maxillary Palpus h". 



EXTERNAL ANATOMY OF INSECTS. 363 

of Aphaniptera (Pulex L.), in which the ordinary 
Tropin are replaced by a bivalve beak, between the 
valves of which there appear to be three lancets a . 
It includes the Lamina, Scalpella, and Ligula. 

A Lamina (the Lamina). Two corneous plates which 
are laterally affixed to the mouth of a flea, proba- 
bly representing the Mandibula of the perfect 
mouth, which somewhat resemble the beak of a 
bird b . 

B Scalpella (the Lancets). The two upper or outer 
instruments, probably for making an incision in the 
skin ; these are flat and acute, and seem to repre- 
sent the Maxilla of the perfect mouth c . 

C Ligula (the Ligula). A capillary instrument between 
the lancets; probably representing the tongue of 
the perfect mouth d . 

6. Rostellum (the Rostellum). The oral instruments 
of Pediculus and some other Aptera, in which the 
ordinary Tropin are replaced by an exarticulate re- 
tractile tube, which exerts a retractile siphuncle. 
It includes the Tubulus and Siphujiculus. 

A Tubulus (the Tubulet). The tube or retractile base 
of the Rostellum. 

B Siphunculus (the Siphuncle). The real instrument 
of suction, which when unemployed is retracted 
within the tubulet. 

Besides the above variations from the type of what I 
call a Perfect Mouth, there are others in which the parts 
of the Trunk appear to aid in the conversion of the food, 

a Plate VII. Fig. 8. *> Unci. c'. 

c Ibid. cl'. Maxillary Palpi h". d Ibid. e'. 



364. EXTERNAL ANATOMY OF INSECTS. 

and become a kind of accessory Labium, Maxilla, SfC. 
TJius in the Myriapods, the anterior pair of legs assume 
a Maxillary farm and office a ; the Presternum those of a 
Labium b : in the Arachnida, also, the anterior Coxae are 
accessory Maxillae. In this Class, likewise, as has been 
more than once observed c , the representatives of the inte- 
rior pair of Antennae of the Crustacea, are thought 
to assume the form and the functions of suctorious Man- 
dibles d . 

ii. Facies (the Face). The upper surface of the head e . 
It includes all the parts that lie between its junction 
with the Prothorax and the Labrum: viz. Nasus, 
Postnasus, From, Vertex, Occiput, Gence, Tempora, 
Ocidi, Siemmata, and Antenna?. 

1 . Nasus (the Nose). That portion of the face, often 

elevated and remarkable, situated between the La- 
brum, Postnasus, and Gence, and with which the 
Labrum articulates; called by Fabricius the Cly- 
peus f . It includes the Rhinarium. 
A Rhinarium (the Nostril-piece). The space between 
the anterior margin of the Nasus and the Labrum, 
in which, in vertebrate animals, the nostrils are often 
situated g . — N. B. This is remarkable in some La- 
mellicorn beetles, as Anoplognathus Leach. In Ne- 
crophorus, and some others, it is membranous. 

2. Postnasus (the Postnasus). That part of the Face 

immediately contiguous to the Antenna, that lies 



a Plate VII. Fig. 11, 13./'. " Ibid. Fig. 11. d'. 

c See above, p. 18, &c. f ' Plate VI. Fig. 10. c'. 

e Plate VI. Fig. 1, 4, 10. a. * Ibid. a. 
* Ibid. s'. 



EXTERNAL ANATOMY OF INSECTS. 3G5 

behind the Nasus, when distinctly marked out. — 
Ex. Sagra, Prosopis. 

3. Frons (the Front). That part of the Face which 

lies behind the Postnasus, and usually between the 
posterior part of the eyes. This is sometimes the 
region of the Stem?7iata ; or they are partly in this 
or partly in the Vertex a . 

4. Vertex (the Vertex). The horizontal part of the Fa- 

des, next the front, that lies behind the eyes and 
between the temples b . This also is often the region 
of the Stemmata. 

5. Occiput (the Occiput). The back part of the head 

when it is vertical, or nearly so, to its point of junc- 
tion with the trunk . — Ex. Meloe, Ripiphorus, 
Hymenoptera, Diptera. 

6. Genje (the Cheeks). Those parts which lie on the 

outside of the anterior half of the eyes, and inter- 
vene also between them and the Mandibular d . 

7. Tempora (the Temples). Those parts which lie on 

the outside of the posterior half of the eyes, between 
which the Frons and Vertex intervene e . 

8. Oculi (the Eyes). The principal organs of sight, 

most commonly two in number, placed in the sides 
of the head. In the majority they are compound, 
consisting of hexagonal lenses. In the Arachnida 
they are simple f . 
A Canthus (the Canthus). A process of the face, which 
enters the notch or sinus of the eye &. — Ex. Scara- 
bamsL., Cerambyx L. 

9. Stemmata (the Eyelets). Two, or more commonly 

a Plate VL c. b Ibid. d. c Ibid. e. d Ibid. f. 

e Ibid. g. f Plates VI. VII. and XXVI. h. 

E Plate VI. Fig. I. and VII. Fig. 2. h'. 



366 EXTERNAL ANATOMY OF INSECTS. 

three, convex, crystalline, simple eyes, observable 
in the Frons or Vertex, or common to both a . — Ex. 
Orthoptera, Hemiptera, Hyme7ioptera. 

10. Antennae (the Antennae). Two moveable and joint- 
ed sensiferous organs, situated in the space between 
or before the eyes, but in no instance behind them b . 
They include the Torulus, Scapus, Pedicellus, and 
Clavola. 

A Torulus (the Bed). The cavity or socket in which 
the base of the Antenna is planted . 

B Scapus (the Scape). The first and in many cases the 
most conspicuous joint of the Antennce A . It in- 
cludes the Bulbus. 

a Bulbus (the Bulb). The base of the Scapus, by which it 
inosculates in the Torulus, often subglobose, and look- 
ing like a distinct joint e . It acts the part of a Botula, 
being the pivot upon which the Antenna turns. 

C Pedicellus (the Pedicel). The second joint of the 
Antenna f : in some insects acting also the part of a 
Rotida in the socket of the Scapus, to give separate 
motion to the Clavola. 

D Clavola (the Clavolet). The remaining joints of the 
Antenna taken together s . It includes the Capitidum. 

a Capitulum (the Knob). The last joints of the Cla- 
vola when suddenly larger than the rest h . 

iii. Subfacies (the Subface). The lower surface or under- 
side of the head '. It includes the Lora and Jugulum. 

* Plate VI. Fig. 4, 10, VII. Fig. 1,2, 4. and XXVI. Fig. 3D — 41.1. 

b Plates XL XII. and XXV. 

c Plate VI. Fig. 1, 2. and VII. Fig. 1. i'. 

d Ibid. XII. Fig. 6, 9. k'. e Ibid. 1". ' Ibid. 1. 

c Ibid. Fig. 6. m'. h Ibid. Fig. 6, 8-10. m". 

1 Plate VI. Fig. 2, 8. e. 



EXTERNAL ANATOMY OF INSECTS. 367 

1. Lora (the Lor a). A corneous angular machine ob- 

servable in the mouth of some insects, upon the in- 
termediate angle of which the Mentum sits, and on 
the lateral ones the Cardines of the Maxilla • and 
by means of which the Tropin are pushed forth or 
retracted a . — Ex. Hymenoptera. 

2. Jugulum (the Throat). That part of the subface 

that lies between the temples b . 

iv. Collum (the Neck). The constricted posterior part 
of a pedunculate head, by which it inosculates in 
the trunk c . It includes the Nucha, Gula, and 
Myoglyph ides. 

1. Nucha (the Naj)e). The upper part of the neck d . 

It includes the Myoglyphidcs. 
A Myoglyphides (the Muscle- notches). Notches in the 
posterior margin of the neck, usually two in num- 
ber, observable in Coleopterous insects, to which the 
levator muscles are attached e . 

2. Gula (the Gula). The lower part of the neck f . 

v. Cephalophragma (the Cephalophragm). A Y-shaped 
partition that divides the head internally in Locust a 
Leach, into two chambers, an anterior and posterior. 

II. TRUNCUS (The Trunk). 

The Trunk is the intermediate section of the body, 
which lies between the Head and the Abdomen s . It in- 
cludes the ManitruncuS) and the Alitruncus b . 

a Plate VII. Fig. 2. 1. Mon. Ap. Avgl. i. t. xiii./. V. a, e. 

b Plate VI. Fig. 3. m. ' ; Ibid. i. d Ibid. n. 

£ Plate XXVII. Fig, 1 , 3, 4. n'. f Plate VI. Fig. 2. o. 

« Plate IX. Fig. 7, 10, 1 1, &c. and XVI. Fig. 4, 8. B. 

*> M. Chabrier, in his admirable Memoires sitr le Vol des Insectes, 



368 EXTERNAL ANATOMY OF INSECTS. 

i. Manitruncus (the Manitrunk). The anterior seg-> 
merit of the trunk, in which the head inosculates, or 
on which it turns a * It includes the ProtJwrax and 
Antepectus. 

1. Prothorax (the Prothorax). 'The upper part or 

the shield of the manitrunk, in Coleoptera, Ortho- 
ptera, &c. called by way of eminence the Tho- 
rax b . It includes the Ora, Patagia, Umboties, and 
Phragma. 

A Ora (the Ora). The inflexed or inferior lateral mar- 
gin of the Prothorax, separated in many genera 
from the Antepectus by a suture c . 

B Patagia (the Patagia). Two corneous scales ob- 
servable in Lepidoptera, fixed on each side of the 
trunk, just behind the head, and covered with a 
long tuft of hair d . 

C Umbones (the Bosses). Two moveable bosses sur- 
mounted by a spine, with which the Prothorax of 
the Coleopterous genus Macropus is armed. 

D Phragma (the Phragm). The Septum that closes 
the posterior orifice of the Prothorax in Gryllotalpa 
Latr. 

2. Antepectus (the Forebreast). The underside or 

breastplate of the manitrunk, and the bed of the 
Arms e . It includes the Spiracula Antepectoralia, 
Prosternum, Antefurca, and Brachia. 
A Spiracula Antepectorali a (the Antepectoral Spira- 
cles). A pair of breathing-pores fixed in the mem- 
uses the term Tronc Alifere, which suggested the terms here em- 
ployed. 

» Plate IX. Fig. 3, 12, 16, &c. b Ibid. Fig. 1, 2, 10, 11, &e. 
e Ibid. Fig. 2. a'. <* Ibid. IX. Fig. 4. 

e Ibid. VIII. Fig. 3, 11. 



EXTERNAL ANATOMY OF INSECTS. 369 

brane that connects the Antepectus with the Medi- 

pectus a . 
B Prosternum (the Forebreast-bone). A longitudinal 

or other elevation of the Antepectus between the 

Brachia b . 
C Antefurca (the Antefurca). An internal vertical 

process of the Antepectus, consisting usually of two 

branches, which afford a point of attachment to 

muscles of the Brachia c . 
D Brachia (the Arms). The first pair of legs of Hex- 

apods, the direction of which is usually towards the 

head ; when spoken of with the other legs, called 

the Forelegs d . They include the Clavicula, Scapida, 

Humerus, Cubitus, and Manus. 
a Clavjctjxa: (the Clavicle). Thejirst joint of the Bra- 

chium, answering to the Coxa in the legs. 
b Scapula (the Scapula). The second ]6mt of the Bra- 

chium, answering to the Trochanter in the legs. 
c Humerus (the Humerus). The third and elongated 

joint of the Brackium, answering to the Femur in 

the legs. 
d Cubitus (the Cubitus). The fourth and elongated 

joint, answering to the Tibia in the legs. It includes 

the Coronula and Calcaria. 
A Coronula (the Coronula). A coronet or semicoro- 

net of spines, observable at the apex of the Cubitus 



* Plate XXIX. Fig. 12. c. b Plate VIII. Fig. 2, 11. d'. 

c Plate XXII. Fig. 7- e. 

d M. Latreille, in his Organisation Exterieure des Insectes {Mem. 
du Mus. viii. 198.) proposes calling the fore-legs of Hexapods Pro- 
pedes; but having long ago applied this term to the false legs of ca- 
terpillars (see above, Vol. II. p. 288. &c), we shall not adopt it. 

VOL. III. 2 B 



o/O EXTERNAL ANATOltt* OJb IQDsKUJCS. 

or Tibia of some insects. — Ex. Dilophus Latr., 
Fulgora L. 
B Calcaria (the Spurs). See the definition under Pedes 

Postici. They include the Velum. 
a Velum (the Velum). A membrane attached to the 

inner side of the cubital spur in Apis L. a 
e Manus (the Hand). The terminal jointed portion of 
the Brachium. answering to the Tarsus in the legs b . 
It includes the Pulvilli, Palma, and Digitus. 
f Pulvilli (the Pulvilli). See definition under P<?des 

Posz'z'c?. 
g Palma (the Palm). The first joint of the Manus, 
when longer and broader than the subsequent ones, 
or otherwise remarkable; answering to the Planta 
in the legs c . 
A Digitus (the Finger). See definition under Pedes 

Postici. It includes the Ungula. 
a Ungula (the Claiso-joint). See definition under Pedes 
Postici. It includes the Pollex, Unguiculi, and 
Palmula. 
a Pollex (the Thumb). A small accessory joint, at- 
tached to the Ungula of the Manus in Mantis F. 
j3 Unguiculi (the Clows). See definition under Pedes 

Postici. 
y Palmula (the Palmlet). A minute accessory joint 
between the claws, answering to the Plantula in the 
legs. It includes the Pscudonychia. 
* Pseudonychia (the Spurious Clows). See definition 
under Pedes Postici. 



a Plate XXVII. Fig. 36. a: *> Plate XV. Fig. G— 9. 

c Plate XXVII. Fig. 59. a. 



EXTERNAL ANATOMY OF INSECTS. 371 

ii. Alttruncus (the Alitrunk). The posterior segment 
of the trunk to which the abdomen is affixed, and 
which bears the legs and wings a . It includes the 
Mesothorax and Medipectus, and the Metathorax 
and Postpectus. 

1. Mesothorax (the Mesothorax). That segment of 
the alitrunk which bears the Elytra, or the anterior 
pair of wings, and the intermediate pair of legs b . 
It includes the Collare, Prophragma, Dorsolum, 
Scutellum, Frcenum, and Pnystega. 

A Collare (the Collar). Thejirst or anterior piece of 
the Mesothorax. In most insects that have a con- 
spicuous Prothorax, as the Coleoptera, this piece 
appears scarcely to have a representative ; but in the 
Libellulina it co-exists with it, and is more con- 
spicuous c . It is particularly remarkable in Hyme- 
7ioptera and Diptera. 

B Prophragma (the Prophragm). A partition of an 
elastic substance, rather horny, connected posteriorly 
with the Dorsolum, which passes down into the an- 
terior cavity of the alitrunk, of which it forms the 

" Plate VIII. Fig. 3, 4, 12—14, 16, 17- IX. Fig. 1, 3, 7, 8, 
10—12, 15. ,J Ibid. r. 

•= Plate IX. Fig. 7, 11, 12, 15, 19. g. The Collare of Hymeno- 
ptera and Diptera has usually been regarded as representing the 
Prothorax of Coleoptera, Orthoptera, &c But this difference obtains 
between them — the latter evidently belongs to the Manilrunk, and 
its muscles do not appertain at all to the Alitrunk ; whereas the Col- 
lare as evidently is a part of the latter, its muscles belong to it, and 
its functions in assisting in flight are important. These reasons, and 
others we shall state hereafter, induced us long ago to consider this 
part as not representing the Prothorax ; and they seem to have in- 
duced M.Chabrier almost to adopt a similar opinion. Sur le Vol des 
Imectes. Ann. du Mus. 3cme Ann. 414. et 4eme Ann. 54 — . 
2B 2 



372 EXTERNAL ANATOMY OF INSECTS. 

upper separation from that of the manitrunk. It 
affords a point of attachment to several muscles of 
the wings, &c. a 

C Dorsolum (the Dorslet). The piece which lies be- 
tween the Collare and Scutellum, to which the pro- 
praghm is anteriorly attached, and which bears the 
upper or anterior organs of flight b . It includes 
the Pteropega, Elytra, Tegmina, Hemelytra, Ales 
Super iores, and Tegulcc. 

a Pteropega (the Wing-socket). The space in which 
the organs for flight are planted. That for the se- 
condary or under-wings is in the Metathorax . 

b Elytra (the Elytra). The upper organs for flight, 
when they are without nervures, and uniformly of 
a thicker harder substance than membrane whether 
corneous, or coriaceous ; lined by a fine membrane ; 
and when closed, united by the longitudinal suture d . 
They include the Axis, Sutura, Epipleura, Alula, 
and Hypoderma, and are peculiar to the Coleoptera 
and Dermaptera. 

A Axis (the Axis). A small, prominent, irregular pro- 
cess of the base of the Elytrum, upon which it turns, 
and by the intervention of which it is affixed to the 
Dorsolum, in the anterior wing-socket e . 

B Sutura (the Suture). The conflux of the sutural or 
inner margins of the two Elytra, where when closed 
they unite longitudinally f . 

» Plate XXII. Fig. 8, 11. A'. 

" Ibid. Fig. 8. Plate VIII. Fig. 3, 12, 14, 16. IX. Fig. 1, 7, 8, 
10—12, 15, 19, 21. i. 
c Plate VIII. Fig. 14, 20. IX. Fig. 11, 12. and XXII. Fig. 8. b" . 
d Plate X. Fig. 1.; and XXVIII. Fig. 1—8, 10. 
e Plate XXVIII. Fig. 3—5. b'". f Plate X. Fig. 1. d" . 



EXTERNAL ANATOMY OF INSECTS. 373 

C Epipleura (the Epipleura). The inflexed accessory 
margin observable underneath in many Elytra, 
which covers the sides of the alitrunk and abdo- 
men a . 

D Alula (the Winglet). A small, membranous, wing- 
like appendage, attached to the Elytrum on one side 
and the Frcemim on the other ; which probably 
serves to prevent the dislocation of the former b . — 
Ex. Dytiscus. N. B. A similar organ for a similar 
purpose is to be found in Blatta and the Diptera. 

E Hypoderma (the Hypoderma). The skin, in some 
species beautifully coloured, that lines the Elytra c . 
N. B. This skin is also found in some Hemelytra, but 
not in Tegmina. 

c Tegmina (the Tegmina). The upper organs of flight, 
when of a uniform coriaceous or pergameneous tex- 
ture, veined with nervures, and lapping over each 
other d . Ex. Orthoptera e . 

d Hemelytra (the Hemelytra). The upper organs of 
flight, when they are corneous or coriaceous at the 
base and membranous at the apex f . — Ex. The 
heteropterous Hemiptera. They include the Co- 
rium and Membrana. 

A Corium (the Cor ium). The corneous or coriaceous 
part of the Hemelytrum s . 



a Plate XXVIII. Fig. 6—8. d'". h Plate XXIII. Fig. 6. e". 

« Plate XXVIII. Fig. 2. a'". 

d Ibid. Fig. 19. and Plate X. Fig. 2. 

e The upper organs of flight of many of the homopterous section 
of the Hemiptera seem altogether membranous, and may almost be 
included under the term Alee Superiores. 

f Plate X. Fig. 3. E Ibid./'". 



374 EXTERNAL ANATOMY OF INSECTS. 

B Membrana (the Membrane). The membranous part 
of the same a . 

e Al.e Superiores vel Primarle (the Upper ox Pri- 
mary Wings). The upper or anterior organs of 
flight when formed of membrane, or of the same 
substance with the under-wings b . They include 
the Axes, Area, Areola, Neurce, Stigma, Parastigma, 
and Lobuli. 

A Axes (the Axes). Several osseous or horny pieces, 
by which the wing is connected with the Dorsolum c . 
One usually to each area. 

B Are^e (the Areas). The larger longitudinal spaces 
into which the wing may be divided d . They in- 
clude the Area Costalis, Intermedia, and Analis. 

a Area Costalis (the Costal Area). That part of the 
wing lying between the anterior margin and the 
post-costal nervure e . In Hymenoptera and Di- 
plera it includes all the space bounded by the ner- 
vures that spring from the postcostal. 

b Area Intermedia (the Intermediate Area). That 
part of the wing lying between the costal area and 
the interno-medial nervure, in Dipt era ; or the 
Anal in Orthoptera, Hemiptera, Hymenoptera, &c. f 

c Area Analis (the Anal Area). All that part of the 
wing which in Diplera lies between the interno- 



a Plate X. Fig. 3. g". 

'' Ibid. Fig. 5—9, 11-15. and Plate XXVIII. Fig. 18. 

« Ibid. //", 

d N.B. In the Plate the Costal Area is red, the Intermediate white, 
and the Anal yellow. When the Hemelytra are considered as divided 
into Areas, the Membrana might be denominated the Apical Area. 

e Plats X. Fig. % 3, b\ f Ibid. c\ 



EXTERNAL ANATOMY OF INSECTS'. 375 

media] nervure ; or in Orthoptera, &c. between the 
anal nervure and the posterior margin a . 

C Areolae (the Areolets). The smaller spaces into 
which the wing is divided by the nervures. They 
include the Areola? Basilares, Media?, and Apicales. 

a Areolae Basilares (the Basal Areolets). The pa- 
rallel areolets of the base of the wing b . 

b Areolae Mediae (the Middle Areolets). The areolets 
of the wing that lie between the basal areolets and 
the apical c , 

c Areolae Apicales (the Apical Areolets). Those 
areolets of the wing that terminate in or very near 
the apex d . 

D Neurje (the Nervures). Corneous tubes, for expand- 
ing the wing and keeping it tense, and to afford 
protection to the air-vessels — commonly called the 
Nerves. They include the Neura Costalis, Post- 
costalis, Mediastina, Eocterno-media, Interno-media, 
Analis, Axillaris, and Spuria. 

a Neura Costalis (the Costal Nervure). The first 
principal nervure of the wing, close to or forming 
the anterior margin in Lepidoptera, Hymenoptera^ 
and Diptera; but sometimes remote from it in Teg- 
mina e . It includes the Phialum and Hamus. 
a, Phialum (the Phial). A little bag to receive fluid at 
the will of the insect, by which the weight of the 
wing is increased. It is found also in the under- 
wings in Coleoptera f . 

a Plate X. Fig. % 3. d: '• Ibid. Fig. 7—15. e\ 

c Ibid./. <> Ibid, g: e Ibid. h\ 

f Chabrier Sur le Vol des Inseeies, Ann. du Mm. 3eme ann. i'23,. 
4eme ann. 325 — . 3d Cahier 78. 



376 EXTERNAL ANATOMY OF INSECTS. 

/3 Hamus (the Hook). A Hook fixed to the Costal 
Nervure, near its base on the under-side, in the 
wings of some Lepidoptera, in which the tendon 
runs a . 
b Neura Postcostalis (the Postcostal Nervure). The 
second principal, and often strongest, nervure of 
the wing b . It includes the Neurce Subcostales. 
« Neurje Subcostales (the Subcostal Nervures). Ner- 
vures springing from the under-side of the post- 
costal nervure, or from each other; called the Jirst, 
second, third, &c. in the order of their occurrence c . 
c Neura Mediastina {Mediastinal Nerwme). A usu- 
ally slender nervure, springing from near the base 
of the postcostal ; between which and the costal it 
intervenes. In the Lepidoptera Diurna, however, 
it is often a strong nervure d . 
d Neura Externo-media (the Externo-medial Ner- 
vure). The third principal nervure of the wing e . 
It includes the Neura Subexterno-media. 
a Neura Subexterno-media (the Subexterno-medial 
Nervure). A nervure that in some cases intervenes 
between the externo-medial and interno-medial f . 
e Neura Interno-media (the Interno-medial Nervure). 
The fourth principal nervure s . It includes the 
Neura Subinterno-media. 
a Neura Subinterno-media (the Subinterno-medial 
Nervure). A nervure that sometimes intervenes 
between the externo-medial and the anal h . 

a Linn. Trans, i. t. xiii./. 2. 3. d. h Plate X. Fig. 5—15. i: 

c Ibid, a *. d Ibid. Fig. 6. k\ « Ibid. l\ 

i Ibid. Fig. 5, 6, 13.6*. g Ibid. Fig. 5—15. m\ 
h Ibid. Fig. 5, 6,13. c*. 



EXTERNAL ANATOMY OF INSECTS. 377 

f Neura Analis (the Anal Nervure). The principal 
nervure nearest the interior or posterior margin, 
with which it includes a space often subtriangular, 
traversed in most Diptera and many Hymenoptera 
by another nervure; and in many Tegmina and 
Hemelytra by several a . In these kinds of upper- 
wing it is in many cases accompanied by a fold ; and 
the part between it and the interior margin seems 
often capable of separate motion. 
g Neura Axillari s (the Axillary Nervure). The short 
nervure, where there is only one, intervening be- 
tween the anal nervure and the interior margin : 
replaced in some Muscidte by a spurious ner- 
vure 5 . 

h Neur^e SpuRiiE (the Spurious Nervures). Very ob- 
solete nervures, sometimes found in addition to 
those usually occurring; as in Syrphus . 

E Stigma (the Stigma). A corneous spot or plate, sup- 
posed to contain fluid, in the anterior margin of the 
upper wings; often produced by the conflux of the 
costal and postcostal nervures d . 

F Parastigma (the Parastigma). A corneous spot be- 
tween the costal and postcostal nervures, distinct 
from the Stigma observable in the Libellulina. 

G Lobuli (Lobuli). One or more rounded portions of 
the base of the wing, separated from the rest by fis- 
sures peculiar to the Muscidce, and the under-wings 
of some Hymenoptera e . 

f Tegulte (the Tegidce). Small corneous concavo-con- 

a Plate X. Fig. 5 — 15. n\ b Ibid. o\ 

c Ibid. Fig. 14. p: d Ibid. Fig. 11. m '". 

e Ibid. Fig. 14,15. ri" . 



378 EXTERNAL ANATOMY OF INSECTS. 

vex scales, which in many Orders, particularly Hy- 
menoptera, cover and defend the base of the Upper- 
Wings a . 
D Scutellum (the Scutcllum). A piece, visually tri- 
angular, which follows the Dorsohmi; and in Co- 
leoptcra is often only a continuation of it — placed 
between the base of the Elytra or upper- 
wings b . 
E Frgenum (the Frcenum). A piece that lies under the 
lateral margin of the Scutellum and Dorsolum, or is 
adjacent to it; and which in many cases connects 
with the base of the upper organs of flight, so as to 
prevent their dislocation, by being pushed too far 
outwards . 
F Pnysteg a (the Pnystega). A corneous scale or plate, 
which covers certain pneumatic vessels, usually 
supported by the Scapularia, in Libellulina, &c. be- 
coming dorsal d . 
1. Medipectus (the Mid-breast). The underside of the 
Jvrst segment of the alitrunk e . It includes the 
Peristethium, Scapular ia, Mesosternum, Medifurca, 
and Pedes Inter medii. 
A Peristethium (the Peristethium). The anterior 
piece of the Medipectus, which intervenes between 
the Brachia and mid-legs f . 
B Scapularia (the Scapulars). Two pieces, one on 
each side the Medipectus, which succeed the Peri- 
stethium, and lie between the midlegs and the Pte- 

■ Plate IX. Fig. 5, 11. g" . * Plates VIII. IX. XXVIII. k\ 

c Ibid./'. d Plate IX. Fig. 7. m l . 

e Plate VIII. Fig. 4, 13, 17.; and IX. Fig. 3, 8, 12. d. 
f Ibid, ri. 



EXTERNAL ANATOMY OF INSECTS. 379 

ropega or wing-socket a . It includes the Spiracula 
Scapidaria. 

a, Spiracula Scapularia (the Scapular Spiracles). 
Two spiracles observable, one in each scapular, in 
Acrida laurifolia, &c. 

C Mesosternum (the Mid-breastone). The elevated 
and central part of the Mcdipectus, between the mid- 
legs, often terminating anteriorly in amucro; some- 
times, as in Plater, in a cavity, receiving the mu- 
cro of the Presternum b . 

D Medifurca (the Medifurca). A branching vertical 
process of the Endosternum, which serves as the 
point of attachment to the muscles that move the 
midlegs c . 

E Pedks Intermedii (the Mid-legs). The intermediate 
pair of legs, consisting of the same parts as the 
posterior legs d . 

3. Metathorax (the Metathorax). The posterior seg- 
ment of the Alitruncus e . It includes the Meso- 
pkragma, Postdorsolum, Post scut ellum, Postfrcenum, 
Pleurce, and Metaphragma. 

a Mesophragma (the Mesophragm). A partition of a 
firm consistence, connected by its posterior margin 
with the Postdorsolum, and passing down vertically 
into the mid-chest; serving as a point of attach- 
ment to several of the muscles that move the 
wings f . This, with the prophragm, forms the an- 

• Plates VIII. IX. o'. b Plate VIII. Fig. 4, 8, 13, 17. p. 

c Plate XXII. Fig. 6. q . d Plate XVI. Fig. 4—6. r . 
e Plate VIII. Fig. 3, 12.; and IX. Fig. 1, 7, 10, 11, \% 
15. e. 
s Plate XXII. Fig. 9, 11./. 



380 EXTERNAL ANATOMY OF INSECTS. 

terior cavity of the alitrunk, and with the meta- 
phragm it forms the posterior cavity. 

b Postdorsolum (the Postdorsolum). The middle- 
piece between the mesophragm and the Postscu- 
tellum. In Coleoptera it consists of a tense elastic 
membrane, which is quite covered by the Meso- 
thorax a . 

c Postscutellum (the Postscutellum). A narrow chan- 
nel running from the Dorsolum to the Abdomen in 
Coleoptera, forming an isosceles triangle reversed. 
In other orders it is either a triangular elevation of 
the middle of the posterior part of the Postdorsolum, 
or a distinct triangular piece b . 

d Postfrcenum (the Postfrcenum). In Coleoptera the 
part of the Metathorax in which the Postscutellum 
lies, at first nearly horizontal, but posteriorly it takes 
a vertical direction towards the abdomen. In ge- 
neral it may be defined, the part that intervenes 
between the Postscutellum and the Abdomen; and 
which in many cases is connected with the posterior 
basal margin of the under-wings, and prevents their 
being pushed too far forwards c . 

e Pleurae (the Pleurce). The space behind the scapu- 
lars, on which the lower organs of flight are fixed d . 
They include the Al<£ Inferiores. 

A Al^e Inferiores (the Under-wings). The lower or 
secondary pair of organs for flight e . They include 
the Commissura, Tendo, Hamuli, Pterygium, Alula, 
and Halteres. 

» Plate VIII. Fig. 3, 12, 20. and IX. Fig. 7, 10-12, 15, 20. t. 
b Ibid. u. « Plates VIII. IX. XXVIII v. 

d Plates VIII. and IX. w. e Plate X. Fig. 4, 10. 



EXTERNAL ANATOMY OF INSECTS; 381 

a Commissura (the Commissura). A joint in the costal 
nervure of the wings of Coleoptera, where they bend 
to take a transverse fold a . 

b Tendo (the Tendon). A strong bristle, or bristles 
observable at the base underneath in the under- 
wings of many Lepidoptera, which plays in the Ha- 
mus of the upper-wings b . 

c Hamuli (the Hooklets). Very minute hooks in the 
middle of the anterior margin, observable in some 
Hymenoptera, by which the under-wing is fixed to 
the upper, to cause both to act as one organ in 
flight c . 

d Pterygium (the Pterygium). In under-wings this is 
a small wing-like appendage, fixed at the base of 
the wing in some Lepidoptera d . 

e Alula (the Winglet). A small concavo-convex sca- 
rious appendage, fixed behind the wings at their 
base, in many Diptera e . 

f Halteres (the Poisers). Small capitate processes or 
organs, observable under the wings of Diptera^ at- 
tended by a spiracle f . 

B Metapnystega (the Metapnystega). A corneous 
scale or lamina that covers the pneumatic organs 
in the Mctatlwrax, situated sometimes in the Plea- 
rce, as in the Coleoptera ; at others in the Postfrce- 
num, as in Tenthredo L. ; and sometimes, as in the 
Libellulina, between that part and the abdomen e . 



a Plate X. Fig. 4. d" . b Linn. Trans, i. t. xin.f. 1. b. 3. a. 

c Kirby Mon. Ap. Angl. i. t. xiii./. 19. 

d De Geer ii. t. ix./. 9. d. " Ibid. vi. t. u.f. 23. a a. 

f Plate IX. Fig. 19. p'". 

g Ibid. Fig, 7. and Plate XXII. Fig. 14. k". 



382 EXiJSxv^AA. ANATOMY OF INSECTS. 

C Metaphragma (the Metaphragm). A nearly verti 
cal septum or partition, attached behind to the 
Postfrcenum, and usually deeply cleft at its apex in 
Coleoptera, of a rather horny consistence, which 
forms the upper separation of the second cavity of 
the Alitrunk from that of the Abdomen*. It affords 
a point of attachment for many muscles of both 
alitrunk and abdomen. It includes the Septula. 
a Septula (the Septula). The lesser ridges and par- 
titions raised on the surfaces of the metaphragm, 
and on those of other parts of the cavities of the 
trunk, serving as points of attachment to various 
muscles b . 
4. Postpectus (the Postpectus). The underside of the 
second segment of the alitrunk c . It includes the 
Mesostethiwn, Parapleurce, Metasternum, Postfurca, 
Opercula, and Pedes Postici. 
A Mesostehium (the Mesostethium). A central piece 
between the intermediate and posterior legs, and 
bounded laterally in Coleoptera by the Parajrteurce 
— along the middle of which, where it exists, the 
Metasternum runs d . 
B Parapleur^e (the Parapleural). Two pieces, one on 
each side of the Postpectus, included between the 
Scapularia, Mesostethium, and Pleura e . They in- 
clude the Spiracida Parapleuritica. 
a Spiracula Parapleuritica (the Parapileuritic Spi- 
racles). Two spiracles, one in each of the Para- 
pleurce of Tetyra f . 

* Plate XXII. Fig. 10, 11. x . b Ibid. Fig. 9—11./". 

c Plates VIII. and IX. /. d Ibid. j/. 

e Ibid. z. i Plate XXIX. Fig. 15. *". 



EXTERNAL ANATOMY OF INSECTS. 383 

C Metasternum (the Melasternum). The central and 
often elevated part of the Mesostet/iium. Its anterior 
niucro, in Coleoptera, often meets the posterior one 
of the Mesosternwn, and sometimes appears to form 
one piece with it, as in Hydrophilus, and many 
Lamellicorn beetles. Sometimes, as in Cetonia vit- 
ticollis, it even passes between the arms, and covers 
the Prosternum, or supplies its place. Behind, it 
often terminates in a bifid mucro. It is not present 
in many Orders : as in the Hymenoptera, Diptera, 
&c. a It includes the Pectines. 

a Pectines (the Pectines). Two moveable processes, 
fixed one on each side by its base below the posterior 
legs to theMeta sternum in Scorpio: on the lower side 
is fixed a series of parallel biarticulate processes, re- 
sembling the teeth of a comb b . 

D Postfurca (the Postfurca). A process of the En- 
dosternum, terminating in three subhorizontal acute 
branches, resembling the letter Y, and forming an 
acute angle with the Endosternum, to which the 
muscles that move the hind-legs, &c. are affixed c , 

E Opercula (the Opercida). Plates that cover the 
vocal spiracles in humming insects ; and likewise 
two large cartilaginous plates fixed to the posterior 
part of the Postpectus, which cover the Tympana 
in male Tettigonia F. d Perhaps these may be re- 
garded as a kind of Metapnystega in a new situ- 
ation. 

F Pedes Postici (the Hind-legs). The pair of legs 

a Plates VIII. IX. of. b Plate XXVII. Fig. 50, 

c Plate XXII. Fig. 3. b f . 

d Plate VIII. Fig. 18; and XXII. Fig. 13. cf. 



384- EXTERNAL ANATOMY OF INSECTS. 

affixed to the postpectus a . They include, the Ace- 
tabulum, Coxa, Trochanter, Femur, Tibia, and 
Tarsus. 
a Acetabulum (the Socket). The socket in the Post- 
pectus in which the leg is planted b . It includes the 
Pessella. 

A Pessella (the Pessella). Two little acute processes, 
fixed one in each, in the socket of the hind-legs in 
male Tettigoniw, which appear designed to keep 
down the Opercida . 

b Coxa (the Hip). Thejirst joint of the leg which 
plays in the socket d . 

c Trochanter (the Trochanter). The second joint of 
the leg, by which the thigh inosculates in the Coxa. 
It appears to have no motion separate from that of 
the thigh. It is sometimes biarticulate e . 

d Femur (the Thigh). The third joint of the leg, long 
and usually compressed f . It includes the Gony- 
theca. 

A Gonytheca (the Knee-pan). A concavity at the apex 
of the thigh, underneath, to receive the base of the 
Tibia ». 

e Tibia (the Shank). The fourth joint of the leg, very 
long, and usually triquetrous h . It includes the 
Epicnemis, Molida, Talus, Calcaria, and Coro- 
nula. 



a Plate XIV. Fig. 5—8. 

b Plate VIII. Fig. 2, 4, 11, 13, &c. o" . « Ibid. Fig. 18. q" . 

A Plate XIV. Fig. G— 8; and XXVII. Fig. 12. p". «= Ibid. q"\ 

f Plate XIV. Fig. 5-8; and XXVII. Fig. 6— 8. /'. 

« Plate XXVII. Fig. 7, 8, 15. ?•'". 

h Plate XIV. Fig. 5—8.*". 



EXTERNAL ANATOMY OF INSECTS. 385 

A Epicnemis (the Epicnemis). An accessory joint at 
the base of the Tibia in many Arachnida, which 
does not appear to have separate motion a . 

B Molula (the Knee-ball). The convex and sometimes 
bent head of the Tibia, armed with a horny pro- 
cess on each side, by which it is attached to the 
thigh b . 

C Talus (the Ankle). The apex of the Tibia, where it 
is united to the Tarsus c . 

D Calcaria (the Spurs). One, two, or more moveable 
spines, inserted usually at the apex of the Tibia; 
and in many Carabi L., Lepidoptera L., and TricJio- 
ptera K., in the middle also. They may be regarded 
as a kind of fingers auxiliary to the Tarsus, and fur- 
nish often an important character in the discrimina- 
tion of genera d . 

E Coronula (the Coromda). A coronet or semicoronet 
oijixed spines observable at the apex of the poste- 
rior Tibia in Fulgora candclaria, &c. 

f Tarsus (the Tarsus). The Jiftli principal portion 
of the legs ; consisting in the majority of insects of 
1 — 5 joints, but in the Phalangidce of sometimes as 
many as 50 e . It includes the Planta, Digitus, and 
Solea. 

A Planta (the Instep). The first joint of the Tarsus is 
so called when it is remarkably long and broad f . 
It includes the Calx. 

* Plate XXVII. Fig. 21. s" . b Ibid. Fig. 9, 10, 16, 17.*"'. 
c Ibid. Fig, 34—36. u". 

d Plate XIV. Fig. 6; and XXVII. Fig. 29— 36. v". 
e Plate XIV. Fig. 5—8; and XXVII. Fig. 44, 45, 62, 63. t". 
f Plate XXVII. Fig. 25, 26, 41. w'" . 
VOL. III. 2 c 



386 EXTERNAL ANATOMY OF INSECTS. 

a Calx (the Heel). The curving part of the Planta, by 

which it inosculates with the Tibia. 
B Digitus (the Toe). The remaining joints of the Tar- 
sus taken together a . It includes the Allux and Un- 
gula. 
a Allux (the Toe-ball). The last joint but one of the 
Tarsus, when remarkable, as in Rhyncophorous 
beetles (Curculio L.) b . 
b Ungula (the Claw-joint). The last joint of the Tarsus, 
which bears the claws c . It includes the Arthrium, 
Unguicidi, and Plantula. 
a Arthrium (the Arthrium). A very minute joint at 
the base of the claw-joint, in most Tetramerous and 
Trimerous beetles d . 
(6 Unguiculi (the Claws). One or two pair of moveable 
incurved claws, which usually arm the apex of the 
Ungula e . 
y Plantula (the Plantula). A minute accessory joint, 
sometimes attached within the claws to the apex of 
the Ungula f . Ex. The Lucanida?. It includes the 
Pseudonychia. 
* Pseudonychia (the Spurious Claws). Two stiff claw- 
like bristles, that terminate the Plantida s. 
C Sole a (the Sole). The underside of the TarsusK It 

includes the Pulvilli. 
a Pulvilli (the Pulvilli). Cushions of short hairs very 
closely set; or of membrane, capable of being in- 

a Plate XXVII. Fig. 25, 26. x". 

b Plate XXVI. Fig. 47, 48 • and XXVII. Fig. 43. r. 

c Ibid, s: <i Plate XXVI. Fig. 47, 48. d*. 

e Plate XXVII. Fig. 37—57. e*. f Ibid. Fig. 56, 57./*. 

s Ibid. Fig. 56. a-ty. b Ibid. Fig. 59. if". 



EXTERNAL ANATOMY OF INSECTS. 387 

flated, or very soft ; or concave plates, which cover 
the underside, or their apex, of the four first joints 
of the Manus or Tarsus, and sometimes even of the 
ends of the Calcaria, as in Cimbex j which act so as 
to produce a vacuum, and enable the animal to sus- 
pend itself, or walk against gravity a . Ex. Timar- 
cha, Bupreslis, Priocera K., the Gryllina, Musci- 
dce, &c. 

III. ABDOMEN (the Abdomen). 

The Abdomen is the third or posterior section of the 
body which follows the Truncus b . It includes the Ter- 
gum, Venter, Petiolus, Cauda, and Anus. 

i. Tergum (the Tergum). The upper or supine surface 
of the abdomen c . It includes the Segment a Dorsa- 
lia, and Pulmonaria. 

1. Segmenta Dorsalia (the Dorsal Segments). Trans- 

verse segments of the back, the sides of which often 
lap over and cover those of the ventral segments d . 

2. Pulmonaria (the Pulmonary Space). Two longitu- 

dinal soft spaces, capable of tension and relaxation, 
one on each side of the back of the abdomen, in 
which, where they exist, the dorsal spiracles are 
planted e . They include the Spiracula Dorsalia. 
a Spiracula Dorsalia (the Dorsal Spiracles). Late- 
ral breathing-pores observable in the dorsal seg- 
ments, often covered by the preceding segment f . 

* Plate XV. Fig. 9 ; and XXVII. Fig. 35, 59—61. f. 

h Plate VIII. Fig. 5, 6, 9, 15, 18, 19. 

c Ibid. Fig. 5, 15. A. d Ibid. A. 

e Ibid. Fig. 5, 9. B'. ' Ibid. Fig. 5, 9, 15. A'. 

2c 2 



388 EXTERNAL ANATOMY OF INSECTS. 

ii. Venter (the Belly). The lower or prone part of the 
abdomen a . It includes the Hypochondria, Epiga- 
strium b , Segmenta Ventralia, and Elastes. 

1. Hypochondria (the Hypochondria). Two portions 

of segments, one on each side; which in some ge- 
nera (Carabus L., &c.) intervene between the first 
intire ventral segment and the posterior part of the 
Postpectus. 

2. Epigastrium (the Epigastrium). The first intire ven- 

tral segment d . It includes the Mucro and Tym- 
pana. 

A Mucro (the Mucro). The central posterior point of 
the Epigastrium observable in many of the Orders, 
which reposes between the posterior legs ; and, ac- 
cording to M. Chabrier, is useful to the insect du- 
ring flight e . 

B Tympana (the Drums). Two deep cavities, contain- 
ing a complex machinery on each side of the Epiga- 
strhim in male Tettigonia?, which are the instruments 
of sound f . 

3. Segmenta Ventralt a (the Ventral Segments). Trans- 

verse sections of the belly s . In Elytrophorous in- 
sects they are usually of a firmer consistence than 
those of the back. They include the Spiracula Ven- 
tralia. 
A Spiracula Ventralia (the Ventral Spiracles). — 

a Plate VIII. Fig. 6, 9, 15. B. 

b The scientific reader must recollect that these terms are em- 
ployed, not because these parts are thought to be true representa- 
tives of the Epigastrium and Hypochondria of vertebrate animals, 
but merely on account of some analogy between them. 

c Plate VIII. Fig. 6. C. * Ibid. B' . e Ibid. B" . 

t Ibid. Fig. 18, 19. C" . 2 Ibid. Fig. 6, 9, 15. E. 



EXTERNAL ANATOMY OF INSECTS. 389 

Breathing-pores observable in some genera in the 
intermediate ventral segments, one on each side a . 
Ex. Dynasles Aloeus, &c. 

4. Elastes (the Elastes). The elastic organs on the 
ventral segments of Machilis polypoda which assist 
this insect in leaping. 

iii. Petiolus (the Footstalk). A slender part by which 
the abdomen of many Hymenoptera is united to 
the trunk, in some genera very long, in others very 
short, and in others wanting b . It includes the Fu- 
niculus, Foramen, Squama, and Nodus. 

1. Funiculus (the Funiculus). A small cartilaginous 
cord, passing through a minute orifice of the Post- 
frcenum, just above the point where the footstalk is 
fixed, to an opposite hole above it, which enables the 
animal the better to elevate or drop the abdomen c . 

2> Foramen (the Foramen). The orifice in the abdo- 
men, through which the above cord passes d . 

3. Squama (the Scale). A vertical flat scale, observable 

on the footstalk of the genus Formica, &c. e 

4. Nodi (the Ktwts). One or more subrotund protube- 

rances of the footstalk in the genus Myrmica f . 

iv, Cauda (the Tail). Where the abdomen grows sud- 
denly slenderer, and terminates in a long jointed 
tail, as in Scorpio and Panorpa s . It includes the 
Centris. 

1. Centris (the Centris). The last inflated joint of the 
tail, terminating in the Sting. 

» Plate VIII. Fig. 9. D' . b Plate IX. Fig. 17, 18. C. 

c Ibid. F 1G . 13. F'. (1 Ibid. G. 

e Ibid. Fig. 17. //'. ' Ibid. Fig. 18. 7'. 

« Plate XV. Fig. 12. Z>. 



390 EXTERNAL ANATOMY OF INSECTS. 

v. Anus (the Anus). The termination of the abdomen, 
consisting of the two last segments. It includes the 
Podex, Hypopygium, Cuius, Ovipositor, and Appen- 
dices. 

1. Podex (the Podex). The last dorsal segment of the 

abdomen a . 

2. Hypopygium (the Hypopygium). The last ventral 

segment of the abdomen b . 

3. Culus (the Cuius). The orifice at the end of the 

anus. 

4. Ovipositor (the Ovipositor). The instrument of 

oviposition, by which the insect conducts the eggs 
to their appropriate nidus, and often bores a way to 
it ; the same instrument is by some genera used as 
a weapon of offence, when it is called the Aculeus c . 
It includes the Unci, Tubulus, Valvce, Vaginula, and 
Terebellce. 

A Unci (the Unci). Two pair of robust organs, the 
upper incurved and the lower recurved, with which 
the anus of Locusta Leach is furnished d . 

B Tubulus (the Tubulus). A tubular ovipositor, con- 
sisting of several pieces often retractile within each 
other, like the tubes of a telescope e . 

C Valv^: (the Valves). Two lateral laminae, often coria- 
ceous, by which the ovipositor when unemployed is 
covered f . 

D Vaginula (the Sheath). A corneous case, with 

* Plate VIII. Fig. 5, 15. K '. b Ibid. Fig. 6, 15, 18. L' . 
« Plate XV. Fig. 18-22; and XVI. Fig. 1—3. 

* Plate XV. Fig. 18. E . 

' Plate XV. Fig. 22; and XVI. Fig. 2 3 3. 
f Ibid. Fig. 20, 21 ; and XVI. Fig. \. F\ 



EXTERNAL ANATOMY OF INSECTS. 391 

two grooves, in which the Terebella or Spicula 
play a . 

E Terebella (the Terebella:). Instruments by which 
the insect saws or bores a passage for its eggs to the 
place in which her instinct directs her to deposit 
them b . 

5. Aculeus (the Sting). The above instrument, when 
fitted for an offensive weapon c . It includes, besides 
the Valvce and Vaginula before defined, the Spicula. 

A Spicula (the Darts). The proper stings which inflict 
the wound : retractile within the sheath, externally ser- 
rulate at the apex d . They include the Retinaculum. 

a Retinaculum (the Retinaculum). A minute horny 
moveable scale or plate with which the darts are fur- 
nished, which prevents their dislocation by being 
shot forth too far e . 

vi. Appendices (the Appendages). Other instruments 
and organs, with which the anus of various insects 
is furnished. They include — the Forceps, Forfex, 
Furca, Styli, Foliola, Flosculus, Caudula?, Fila, Mam- 
nndce, Papilla;, and Siphonuli. 

1. Forceps (the Forceps). A pair of anal organs that 

open and shut transversely, and meet at their inner 
margin, or at the apex. Ex. Forficida. 

2. Forfex (the Forfex). A pair of anal organs, which 

open or shut transversely, and cross each other f . 
Ex. Male of Raphidia Ophiopsis. 

* Plate XV. Fig. 20. G'. 

b Ibid. Fig. 20, 21 ; and XVI. Fig. 1. H". 

c Rirby Mon. Ap. Angl. i. t. xii. Apis **. e. 1. neut.f. 23 — 25; and 
t. xiii./. 27, 28. 

-i Ibid. t. xiri./. 30, 31. e Ibid. a. 

* Plate XV. Fig. 12. L". 



392 EXTERNAL ANATOMY OF INSECTS. 

3. Furca (the Fork). An inflected elastic anal organ, 
ending in a fork, by which the animal is enabled to 
leap a . Ex. Podura. 

4-. Styli (the Styles). Rigid, exarticulate, long and 
narrow anal organs b . Ex. Staphylinus. 

5. Foliola (the Leaflets). Rigid, exarticulate, dilated, 

leaf-like anal organs c . Ex. Libellulina. 

6. Flosculus (the Floret). A small, tubular, lunulate 

anal organ, with a central style d . Fidgora cande- 
laria, &c. 

7. Cerci (the Cerci). Two short, flatfish, sublanceo- 

late, jointed, lateral anal organs e . Ex. Blaita. — 
N.B. Analogous organs are observable in the Gryl- 
lina, but usually conical and without joints f . In 
Gryllus Latr. they are setiform s . 

8. Caudul^: (the Caudtdce). Two or more slender, fili- 

form or setaceous, jointed, flexile anal organs h . Ex. 
Lepisma, Machilis, Ephemera. 

9. Fila (the Threads). Two exarticulate, slender, fili- 

form anal organs '. Ex. Machilis. 

10. Mammulje (the Mammulce). Anal protuberances, 
containing instruments for spinning web k . Ex. 
Araneidce. They include the Fusi. 

11. Fusi (the Spinners). Organs, consisting of two re- 
tractile pieces, issuing from the Mammtdce, and ren- 
dering the threads '. 

■ Plate XV. Fig. 14. M" . b Ibid. Fig. 17- N" . 

' Ibid. Fig. 15. 0" . «• Ibid. Fig. 13. P" . 

p Ibid. Fig. 23. Q". 

f De Geer iii. t. xxii ./. 10. a a. 8 Ibid. I. xxiv./. 2. c; and/. 11. 

h Plate XV. Fig. 16. R" . * Ibid. S" . ' * 

* Ibid. Fig. 10; and Plate XXIII. Fig. 16, 17. T " '. 

> Ibid- Fig. 12. B". 15. 



EXTERNAL ANATOMY OF INSECTS. 393 

12. Siphonuli (the Sipkonets). Truncated, fistular, seti- 
form anal organs, emitting a saccharine fluid a . Ex. 
Aphis. 

You will observe, that when the whole upper-side of 
the Truncus is spoken of, it is called the Thorax; and as 
in Coleoptera, and some other Orders, the whole of the 
Mesothorax except the Scutellum is covered by the Tho- 
rax, and the whole of the Metathorax by the Mesothorax 
and Elytra — the Thoracic shield may without danger of 
mistake be denominated the Thorax, as it has always 
been. When the 'whole under-side of the Trunk is spo- 
ken of, it is called the Pectus. When the three Sternums 
are spoken of together, they may be called the Sternum • 
and the whole interior elevation of the Pectus may be 
called the Endosternum. 

3 De Greer ubi sUpr. t. ni.f. 5,20, 21. c. 



LETTER XXXIV. 



EXTERNAL ANATOMY OF INSECTS. 

THE HEAD, AND ITS PARTS. 

BEFORE I confine my observations to the head of in- 
sects, which I propose to consider separately in the pre- 
sent letter, I must premise a few words upon their body 
in general, or rather its crust, or external integument. 
In this we may notice its substance, general/cm, sculp- 
ture, "pubescence, and composition. 

i. I have already noticed the substance of this integu- 
ment in the preparatory states of insects a ; I shall not, 
therefore, here repeat what I then said, but restrict my- 
self chiefly to the consideration of it as it is found in their 
last state, in which it is usually firmer than in their pre- 
vious stages of existence. In this respect, however, it 
varies much in the different Orders, and even in the dif- 
ferent genera of the same Order. In some Coleopterous 
insects, for instance, it is very hard, and difficult to per- 
forate ; while in others it is soft, flexible, and a pin easily 
passes through it 5 . And in general, from a substance 

a See above, p. 86, 110,243—. 

b Many species of Hister, Curculio L ., Doryphora Illig. are ex- 



EXTERNAL ANATOMY OF INSECTS. 395 

in hardness resembling horn or shell, it passes through 
the intermediate degrees of that of leather and parch- 
ment, almost to a thin membrane. Yet in all cases there 
is enough of rigidity and hardness to answer the princi- 
pal uses of a skeleton — to afford, namely, a sufficient 
point of attachment for the muscles, and to support and 
defend the interior organization; so that the play and 
action of the vital and secretory systems may not be in- 
terrupted or impeded. 

With respect to the principles which enter into the 
composition of this integument, very little seems to be 
known at present ; but few insects having been submitted 
to a chemical analysis. The blister-beetle (Cantharis 
vesicatoria), from its importance in medicine, has, how- 
ever, been more than once analysed; and though the 
products have not been very precisely stated, yet we find 
amongst them phosphate of lime, albumen, and some 
other usual components of the substance of vertebrate 
animals a . But which of these products belong to the 
integument, and which to its contents, cannot be ascer- 
tained, without a separate process for each ; which would 
not, I conceive, be very feasible. The substance, how- 
ever, of the integument of insects, though we know not 
its precise contents, which probably vary in different ge- 
nera, &c, appears not to be exactly of the nature of any 
of those substances after which it has usually been deno- 

tremely hard, while Cantharis Geoffr., Meloe ¥., and Telephones 
Geoffr., are very soft. 

a Thenard Traile de Chimie Elementaire, iii. 637. n. 2005. The 
other products he mentions are — a green oil, a j'ellow substance, a 
black ditto, acetic acid, uric acid, phosphate of magnesia. The vesi- 
cant matter consists of little micaceous laminae soluble in boiling al- 
cohol and oil, but insoluble in water. 



396 EXTERNAL ANATOMY OF INSECTS. 

minated : it is not properly analogous either to real horn, 
shell, skin, or leather, &c. This seems to result from the 
following circumstance : — Most of the excretions of ver- 
tebrate animals, as horn, skin (at least when tanned), 
feathers, wool, hair, &c. when exposed to the action of 
fire liquify, more or less, before they incinerate; emitting 
at the same time a peculiar and disagreeable scent : but 
upon applying this test to the parts of insects of the dif- 
ferent Orders, I found, in every instance, that incinera- 
tion took place without liquefaction, and was unaccom- 
panied by that peculiar scent which distinguishes the 
others. Even the claws, which to the eye appear, as to 
their substance, exactly like those of Mammalia, birds, 
&c. burn without melting, and retain their form after 
red heat. That the insect integument is not calcareous 
like that of the Crustacea, and the shells of Mollusca?, 
you may easily satisfy yourself, by immersing them in an 
acid test. I made this experiment upon portions of in- 
sects of several of the Orders, in an equal mixture of mu- 
riatic acid and water, and the result was, not only that 
all hexapods, but octopods, Arachnida, and even Scolo- 
pcndridce, upon immersion only emitted a few air-bub- 
bles ; while, when the other myriapods, Polydesmus, lu- 
lus, Glomeris, &c. and the Oniscidce, were immersed, a 
violent effervescence took place; proving the different 
nature of their substance. It is remarkable that the two 
great branches of the Myriapods, the Scolopendridce and 
Iulidcc (Chilopoda and Chilognatha Latr.), should in 
this respect be so differently circumstanced — the latter 
having a calcareous integument, and the former not. — 
A further difference distinguishes these two tribes : old 
specimens of the Iididce usually lose their colour and turn 



EXTERNAL ANATOMY OF INSECTS. 397 

white, like Oniscidce ; while those of the Scolopendridce 
retain it. 

ii. The form of insects is so variable, that it can be 
reduced to no other general rules — than that, for the 
most part, the length exceeds the breadth, and the 
breadth the depth, and that the upper surface is usually 
convex. But to these rules there are numerous excep- 
tions. Thus many Tetyra F. (Scutellera Latr.), a kind 
of bug, are as broad as they are long 3 ; in the genus 
Gonyleptes K. b amongst the Aptera, and Epeira cancri- 
Jbrmis, a crab-shaped spider, the breadth exceeds the 
length ; in Cy?iips, and several other Hymenoptera, in 
Acrida K. c (Locust a F.), and other Orthopterous in- 
sects, the depth exceeds the breadth ; and in that singu- 
lar beetle, JEurychora ; the cockroach (Blattci), &c. the 
upper surface is flat. 

iii. The scidpture of the integument of insects is often 
very remarkable; but as this will call for attention here- 
after, I shall only here observe in general, that ornament 
and variety seem not to be the sole object of those eleva- 
tions and depressions which form so prominent a feature 
of many of the animals in question; for by means of these, 
many important purposes, that at first sight do not strike 
the observer, may be served : such as giving firmness 
to the crust in those places where it is most wanted ; di- 

a Coquebert Ittustr. Icon. ii. t. xviii./. 14, 15. 

b Linn. Trans, xii. t. xxii./. 1 6. 

c This name I would give to Locusta F., reserving, with Dr. Leach, 
the latter name to the true locust (Gryllus F.). The name Conoce- 
phalus,by which Locusta¥. has been distinguished, is better restricted 
to those with a conical head. 



398 EXTERNAL ANATOMY OF INSECTS. 

minishing its powers of resistance in others, so that it 
may yield somewhat to the action of the muscles ; in- 
creasing or deducting from the weight of the body, so as 
to produce a proper equipoise during its motions, whe- 
ther on the earth, in the air, or in the water. The de- 
pressions of the outer surface of the crust, in many in- 
stances, produce an elevation of it in the interior, and 
so afford a useful point of attachment to certain muscles. 
This observation seems more especially applicable to 
those excavations that are common to particular tribes 
or genera : thus the dorsal longitudinal channel to be 
met with on the prothorax of most of the Carabi of Linne 
on the inside of the crust have a corresponding ridge. 
In Locusta Dux, also, (a Brazil locust,) the same part 
has four transverse channels, corresponding with which 
on the inside are as many septa, or ridges, to which mus- 
cles are attached; and those larger impressed puncta 
denominated puncta ordinaria, which distinguish the 
same part in Geotrupes and many of the Scarabceida, 
within are elevated, so as to form a kind of ginglymous 
articulation with the base of the anterior coxae. The 
other impressed puncta so often to be seen on the diffe- 
rent parts of various insects, which sometimes so intirely 
cover the surface that scarcely any interval is discover- 
able between them, though in many cases they appear to 
be mere impressions that attenuate but do not perforate 
the crust — yet in others, perhaps equally or more nu- 
merous, they are real pores, which pass through the in- 
tegument. If, for instance, you take the thoracic shield 
of the cockchafer (Melolontha vulgaris), and after re- 
moving the muscle &c, hold it against the light, with 
the inner side towards the eye, you will see the light 



EXTERNAL ANATOMY OF INSECTS. 399 

through every puncture : or take the elytra of Geotrupes 
stercorarius, or any common beetle in which these or- 
gans have punctate striae, and examine them under a 
lens on the inside, and you will see distinctly that the 
punctures pass through the elytrum, and the membrane 
that lines it a . It is not improbable that in the case last 
mentioned these pores may be of use, as the spiracles are 
usually closely covered by the elytra, for the better trans- 
mission of the air to those respiratory organs. Whe- 
ther the pores in the other parts of the body are for 
transpiration, is more than I shall venture to affirm ; but 
as insects sometimes perspire, at least this has been ascer- 
tained with respect to the hive-bee b , this must be by the 
means of some pores. 

iv. The integument of insects is often clothed, either 
partially or generally, with pubescence^ or hairs of vari- 
ous kinds — a circumstance which seems to have more 
than one object. In Parnus, Heterocerus, Gerris, Argy- 
roneta aquatica, and some other aquatic insects, the end 
in view seems to be to keep the water from wetting the 
crust; and in this case the covering of hairs is dense, 
silky, and decumbent. Another object is preventing 
friction from being injurious: thus humble-bees, that 
from their mode of nidification c , are usually more par- 
ticularly exposed to it, are well clothed with hair; and 
in those articulations of insects where much friction takes 
place, we may often observe a dense fringe or coating of 
the same substance. This you may see in the common 



a Plate XXVIII. Fig. 1, 2. 

h Huber Now. Obs. ii. 317. c Vol. I. p. 5Q2— . 



400 EXTERNAL ANATOMY OF INSECTS. 

stag-beetle {Lucanus Cervus), where the thorax receives 
the head ; and very remarkably at the same point in the 
Hercules-beetle (Dynast es Hercules MacLeay) : but be- 
sides these uses, there is probably one more universal, 
which will apply as well to those thinly scattered bristles 
and hairs, here and there one, to be noticed in many 
insects : but concerning this I can only throw out a con- 
jecture, as I do not recollect ever to have seen any ex- 
periments with regard to this use of animal hairs. But 
may they not act as conductors, either to introduce 
some invisible fluid into the body in a positive state, or 
to convey it out, when received by other means, in a ne- 
gative state ? Every one knows that the fur of a cat has 
electric properties, and there may be an important gene- 
ral use of this kind attached to the fur and hairs of ani- 
mals a . But, as I said, I give this as a mere conjecture; 
and only wish it may excite your attention to the subject, 
and put in exercise your natural tact for experiment. 

M. Cuvier regards the hairs of insects as merely a 
continuation of the epidermis, with which they fall when 
the animal changes its skin b ; but this will apply only to 
the hairs of larvae : for the hairs of perfect insects in 
many cases are implanted in a pore, and pass through 
epidermis or crust to the membrane that lines it, in which 
they terminate. 

v. We are now to consider the composition of the in- 
tegument; under which term I would include the diffe- 
rent layers of which it consists, and its articulation. 

n Hair, in the Holy Scriptures, is used as the symbol of strength 
or power. Judges xvi. 17 — . 1 Cor. xi. 10. 
6 Anat. Compar. ii. 624. 



EXTERNAL ANATOMY OF INSECTS. 401 

1. With respect to the Jirst of these circumstances, the 
layers of which the integument consists, it seems to ex- 
hibit some, although not an exact, analogy with the skin, 
rather than the skeleton, of the vertebrate animals a . In 
these last, the skin is stated to consist of four layers. 
Of these the exterior one is the epidermis, or scarf-skin : 
under this is the rcte mucosum, or mucous tissue, which 
gives its colour to the skin ; next follows the papillary 
tissue formed by the extremities of the nerves, and in 
which the sense of touch principally resides ; the last and 
innermost layer is the skin proper, or leather, called Der- 
mis, Derma, or Corium b . Two of these layers M. Cu- 
vier assigns to insects. They have, he observes, in every 
state, a true epidermis* ; and in their state of larva he 
finds that the infinite variety of colours that so adorn 
many of them is produced by a mucous substance ob- 
servable between the epidermis and the muscles d : this 
seems analogous to the rete mucosum. To this, dried 
and mixed with their horny substance, he attributes also 
the colours of the perfect insect : " for," says he, " when 
the Lepidoptera are in the chrysalis, the little coloured 
scales which are to ornament their wings, are then in a 
state of mucosity similar to that which is found under the 
skin of the caterpillar. The colours of the Arachnida," 
he goes on, " are also due to this mucosity : it is disco- 
verable under the skin, and has the appearance of mi- 
nute glandular points of which the shades vary consider- 
ably. But in the Coleoptera, and many other Orders, the 

a Anat. Compar. i. 119. b Ibid. ii. 540. 

c Ibid. .547. d Ibid. 553. 

VOL. III. 2d 



402 EXTERNAL ANATOMY OF INSECTS. 

colours of the skin are mixed in its horny tissue, nearly as 
those of the Testacea are in their calcareous shells a . In 
the perfect insects, therefore, in most cases, we may con- 
sider the epidermis and rete mucosum as together form- 
ing the exterior and coloured integument of insects — 
that part which in the table, since it is not properly an 
epidermis, I have distinguished by the name of Exo- 
derma. 

The learned author just quoted has observed nothing 
under the skin of white-blooded animals that he regards as 
analogous to nervous papillae b . In some parts of insects, 
as in the lamella? of the antennae of the Petalocera, and the 
extremities of the joints, especially the last, of many palpi, 
there is however an appearance of them ; and it seems 
reasonable to suppose that where the sense of touch re- 
sides, there must, even in insects, be something of a pa- 
pillary tissue. 

With regard to the innermost integument of the ver- 
tebrate animals, — the leather, or real skin, — this learned 
comparative anatomist finds nothing analogous to it in 
the integuments of insects c ; but as he does not notice it, 
he appears to have overlooked the substance that lines 
the outer crust, or exoderma, in the Coleoptera and most 
other orders. This is not always easily detected ; but it 
may generally be discovered by breaking, or rather tear- 
ing (not cutting), after having cleared away the muscles, 
any part of the body of an insect. It is always very vi- 
sible on the under side of elytra d , but is not discoverable 



a Anat. Compar. ii. 553. b Ibid. 557. c Ibid. 560. 

4 Plate XXVIII. Fig. 2. a"'. 



EXTERNAL ANATOMY OF INSECTS. 403 

in tegmina. It appears to consist, in many cases, of se- 
veral layers of a whitish membrane, and generally breaks 
into fibres. In some elytra of the larger Dynaslidcs, 
towards the sides the exterior layer is separated from the 
rest by a kind of cellular substance. The fibrous struc- 
ture of this inner skin (which I call the Esoderma) seems 
to give it some affinity to the skin of vertebrate animals a . 
In many parts of the body, however, it appears to be 
merely a thin pellicle. A medical friend, to whom I 
showed specimens of it, thinks it a kind of cellular mem- 
brane. 

2. A few words are next necessary with regard to the 
articulation of the integument, or the mode by which the 
several pieces of which it and its members consist, are 
united to each other. In some, as in several of the parts 
of the head, the occiput, vertex, temples, cheeks, &c. — 
the line of distinction is merely imaginary ; in others an 
impressed line separates a part from its neighbours, as is 
the case with the nose in Vcspa, &c. the head in the 
Arachnida. But m the majority of instances the parts 
are separated by a suture, or form a real joint. The 
kinds of articulation observed by anatomists in vertebrate 
animals do not all occur in insects, and they seem to 
have some peculiar to themselves. Thus, for instance, 
they have no proper suture ; for though they exhibit the 
appearance both of the harmonic and squamose [ecail- 
leuse Cuv.) sutures b , yet these parts being all limited by 

a Anat. Compar. ii. 557. 

b A harmonic suture is when the margins of two flat bones simply 
touch each other, without any intermediate substance; and a squa- 
mose, when the thin margin of one covers that of the other. Anat. 
Com far. i. 124. With regard to the flat portions of the integument of 

2 D 2 



404' EXTERNAL ANATOMY OF INSECTS. 

the esoderma, or skin, above noticed as lining the inte- 
gument, and all admitting a degree of motion more or 
less intense, rather afford examples, as the case may be, 
of other kinds of articulation a . Again, they have no 
proper Enarthrosis, or ball and socket; though the an- 
terior coxa? of the Capricorn-beetles (Cerambyx L.) ap- 
proach very near to this kind of articulation, as will be 
shown more fully in another place. The inosculating 
segments or rings, which distinguish the abdomen, and 
sometimes other parts of insects, are an example of a 
kind of articulation not to be met with in the Vertebrata. 
The ginglymous articulation, in which the prominences 
of the ends of two joints are mutually received by their 
cavities, and which admits only of flexion and extension, 
often prevails in the limbs, &c. of insects ; but in many 
cases the joints are merely suspended to each other by a 
ligament or membrane ; and, in fact, the integument of 
insects, with regard to its articulation, even where the 
joints ginglymate, may be said in general to consist of 
pieces connected by the internal ligament, membrane, or 
skin that lines it; for even in the legs, where the gingly- 
mous articulation is sometimes very remarkable and 
complex, as will be shown to you hereafter, the joints 
are also connected by this substance, as you may see if 
you examine the legs of any Coleopterous insect. 

insects, they have some motion ; whereas a suture is an articulation 
without movement. Ibid. 

a Their connexion by means of a ligament classes them under 
Synneuros-is (Monro On the Bones, Dr. Kirby's edit. 29), but even 
this not strictly, since a common ligament connects them all. Those 
of the trunk, as admitting a slight degree of motion, belong to Am- 
phiarthrosis {Anat. Compar. i. 126), and those of the abdomen, which 
are capable of larger movements, to Diarthrosis {Ibid. 127). 



EXTERNAL ANATOMY OF INSECTS. 405 

The number of articulations or pieces that form the 
integument and its members in these animals, varies 
greatly in different tribes, genera, &c. Thus, in the com- 
mon louse (Pediculus humanus) they scarcely reach fifty, 
while in some cockroaches (Blatta) they amount to more 
than eight times that number. 

Having premised these observations on the external 
anatomy of the body in general, in the remainder of the 
present letter I shall confine myself to the consideration 
of the head and its parts. 

I. The Head of insects, as the principal seat of the 
organs of sensation, must be regarded in them, as well 
as in the vertebrate animals, as the governing part of the 
body. It may be considered with respect to its siib- 
stance,Jigure, composition, superficies.) proportion, direc- 
tion, artimlation with the trunk, motions — and more par- 
ticularly as to its parts and appendages. 

i. With regard to its substance — the head may be said 
in general to be the hardest part of the crust : and it is 
so for very good reasons. In the first place, as it has to 
make way for the rest of the body when the animal moves, 
it is thereby best fitted to overcome such resistance as 
may be opposed by the medium through which it has to 
pass ; in the next, as it bears the organs of manducation, 
it was requisite that it should be sufficiently firm and so- 
lid to support their action, which is often upon very hard 
substances ; and besides this, as no motion of its parts 
inter se, as in the case of the trunk, is requisite to fa- 
cilitate the play of its organs, a thin integument was 
not wanted. 



406 EXTERNAL ANATOMY OV INSECTS. 

ii. The most general law relative to thejigure or shape 
of the head seems to be, that it should approach to that ol 
an equilateral triangle, with its angles rounded, and the 
vertex being the mouth ; and that the vertical diameter 
should be less than the horizontal, whether longitudinal 
or transverse. But the infractions of this law are nume- 
rous and various. Thus, in some insects an isosceles tri- 
angle is represented by the head, the length being greater 
than the breadth ; in others, instead of being flat it is 
compressed, so that the horizontal diameter is less than • 
the vertical; in others, again, it is orbicular, or round and 
depressed ; in others nearly spherical : occasionally it is 
rather cylindrical. In many instances it is very long; 
in others the width exceeds the length. Though often 
narrowest before, in some cases the reverse takes place. 
Its anterior end is often attenuated into a long or short 
snout or rostrum, and its posterior into a long or short 
neck. Its contour, though usually regular, is sometimes 
either cut into lobes, or scooped out into sinuosities. 
But to enumerate minutely all the variations of form 
which take place in the head of insects would be end- 
less; I shall therefore proceed to the next particular. 

iii. The composition of the head is very simple ; for, 
exclusive of its organs, it consists only of a single piece 
or box, without suture or segment, with an aperture at 
the end below to receive the instruments of manducation, 
others for the eyes and stemmata when present, and also 
for the antennas. In the Arachnida, &c, in which the 
head is not separated from the thorax, it is merely a 
plate, the under-side or cavity of which is occupied and 
filled bv the above instruments. 



EXTERNAL ANATOMY OF INSECTS. 407 

iv. With regard to its superficies, the head of insects 
is generally more or less uneven, though in some cases it 
presents no inequalities. In many of the Lamellicorn 
tribes, and a few other individuals, in one sex at least, 
as has been before observed 3 , it is armed with long 
horns, or prominent tubercles ; it is often covered with 
numerous puncta, or pores ; and some of its parts, as the 
nose, after-nose, &c. in particular groups, marked out 
by an impressed line b . In many Hymenoptera, Diptera, 
&c. its upper surface is convex, and the lower concave; 
in others both surfaces are convex. 

v. It is the most general rule, as to its proportion, that 
it shall be smaller than either trunk or abdomen ; but in 
some instances, as in the S. American ant, Atta megace- 
phala, it is much larger than either. 

vi. By the direction of the head, I mean its inclina- 
tion with respect to the prothorax. The most natural 
direction, or that which obtains most generally, is for it 
to form an angle more or less obtuse with the part just 
mentioned. This seems to obtain particularly in Coleo- 
ptera ,■ but in some, as Mylabris, it is infiexed, forming 
an acute angle with it. In the Heteropterous Hemiptera 
(Cimex L. &c.) it is generally in the same line with the 
body, or horizpntal ; and in many Diptera it is vertical. 

vii. We now come to a circumstance which will de- 

a See above, p. 309 — . 

b In the hornet and other wasps, this line on the inside of the 
head furnishes a foundation for a septum, which in the sides of the 
nose is very high, and connects also with the hind part of the head. 



408 EXTERNAL ANATOMY OF INSECTS. 

tain us longer, namely, its articulation with the trunk, 
or rather with its anterior segment, the prothorax. — 
M. Cuvier makes two principal kinds of articulation of 
the head upon the prothorax, in one of which the points 
of contact are solid, and the movement subordinate to 
the configuration of the parts ; in the other, the articula- 
tion is ligamentous, the head and the thorax being united 
and kept together by membranes. 

1. The frst of these kinds of articulation — that by the 
contact of solid parts — takes place, he says, in four dif- 
ferent ways. " In the most common conformation, in 
the part that corresponds to the neck, the head bears 
one or two smooth tubercles, which receive correspond- 
ing cavities of the anterior part of the prothorax observ- 
able in the Lamellicorn and Capricorn beetles. In this 
case the head can move backwards, and the mouth for- 
wards and downwards. The second mode of solid arti- 
culation takes place when the posterior part of the head 
is rounded, and turns upon its axis in a corresponding 
cavity of the anterior part of the prothorax ; as may be 
seen in Curculio, Reduvius, &c. The axis of motion is 
then at the centre of articulation, and the mouth of the 
insect moves equally backwards and forwards, upwards 
and downwards, to right and left. — The third sort of ar- 
ticulation, by solid surfaces, takes place when the head, 
truncated posteriorly, and presenting a flat surface, is 
articulated, sometimes upon a tubercle of the thorax, 
and sometimes upon another flat and corresponding sur- 
face, as in almost all the Hymcnoptera and the majority 
of the Diptera. The disposition of the fourth kind of 
articulation allows the head only the movement of the 
angular hinge (le seid mouvcmcnt de charniere angulaire). 



EXTERNAL ANATOMY OF INSECTS. 409 

The only examples at present known are in some species 
of Attelabus F. The head of these insects terminates 
behind in a round tubercle, received in a corresponding 
cavity of the thorax : the lower margin of this cavity has 
a notch, and permits the movement of the head only in 
one direction a ." 

2. The second kind of articulation, the ligamentous, 
he affirms takes place only in orthopterous and some 
neuropterous insects : " The head in this kind of articula- 
tion is only impeded in its movements towards the back, 
because it is stopped there by the advance of the pro- 
thorax ; but below it is quite free. The membranes or 
ligaments extend from the circuit of the occipital cavity 
to that of the anterior part of the prothorax, which gives 
a great extent to the movement b ." 

When I consider the well-deserved celebrity of the 
great author whose words I have here quoted, and the 
great and useful light that the genius and learning which 
conducted his patient labours and researches have thrown 
over every department of comparative anatomy, — a sci- 
ence he may be almost said to have founded, — I feel the 
most intire reluctance to differ in any thing from an au- 
thority so justly venerable to all lovers of that interesting 
study. But, however great my diffidence and hesitation 
to express an opinion at all opposed to his, the interests 
of truth and science require that I should state those 
particulars in which my own observations, made upon a 
careful examination of various insects of every Order, 
have led to results in some respects different from the 

a Anat. Compar. i, 445—. b Ibid. 447. 



410 EXTERNAL ANATOMY OF INSECTS. 

above. " Aliquando bonus dormitat Homerus " and 
if the Genius of Comparative Anatomy ever nodded, it 
sometimes happened when he was examining the struc- 
ture of insects. An instance of this with regard to the 
mouth of the bee has been noticed by Mr. Savigny 3 ; 
and indeed it is not wonderful that in so extensive an 
undertaking, in which the number of examples to be ex- 
amined upon every branch of his subject must be im- 
mense, that he did not always scrutinize minutely those 
that seemed less important. Every writer on every de- 
partment of Natural Histoiy, especially where the ob- 
jects of research, as in the insect world, are so infinite in 
number, will be liable to such mistakes ; but these will 
meet with due allowance from every candid mind — 
" Hanc veniam damus, petimusque vicissim :" 

and I shall express my trust that you will overlook any 
errors of mine ; and doubtless I shall not be free from 
them — 

" Quas aut incuria fuclit, 

Aut huniana parum cavit natura " 

The two kinds of articulation of the head which our 
learned author has stated as the principal ones, will, I 
think, be found upon examination not so widely distant 
as his expressions seem to indicate ; for in fact in all in- 
sects, as well as the Orthoptera, this part is suspended by 
a membrane or ligament which unites the margins of the 
occipital cavity with those of the anterior one of the pro- 
thorax : thus forming all round some protection to the 

a Mem.sur les Anim. sans Vcrtehr. I. i. 11—. Comp. Anat. Corn- 
par, iii. 314 — . 



EXTERNAL ANATOMY OF INSECTS. 411 

organs that are transmitted from the head through the 
latter part to the rest of the body. Though the head in 
most Orthoptera is not partly received into the cavity 
of the prothorax, as is the case in the Order Coleoptera, 
but is rather suspended to it, yet in some instances, for 
example in the mole-cricket [Gryllotalpa vulgaris), it is 
partially inserted. 

Again : when, in his Jirst mode of articulation by con- 
tact of solid parts, he speaks of one or two smooth tu- 
bercles of the neck, with their corresponding cavities in 
the prothorax, as forming the most common conforma- 
tion, you would expect to find examples of this in very 
many insects ; yet upon a close examination, unless in 
Oryctes nasicomis a , and perhaps in others of the Dy- 
nastidce MacLeay, you would scarcely meet with any 
thing that could be called a tubercle and its correspond- 
ing cavity in the neck or prothorax of any Lamellicorn 
or Capricorn beetle that you might chance to examine. 
You would find, indeed, that the occiput was usually 
smooth and very slippery, as if lubricated ; that in its 
margin were one or two notches (Myoglyphides), with 
muscles attached to them ; that in the former of these 
tribes, the Lamellicorns, it projected on each side so as to 
form a more or less prominent angle ; and that the throat 
(jugulum) was very convex, and lodged in a cavity of the 
lower margin of the prothorax : but further appearances 
of tubercles &c. you would in vain look for even in this 



a It is probable that M. Cuvier took his idea of this first kind of 
articulation, by contact of solid parts, from this individual insect; 
since, besides its very prominent throat, there is on each side of the 
lower part of the occiput a small elevation, or approach to a tu- 
bercle. 



412 EXTERNAL ANATOMY OF INSECTS. 

tribe ; and in the Capricoms you would find that the ge- 
neral conformation in this respect belonged to our learned 
author's second mode of solid articulation, resembling 
that of the majority of the weevils {Curculio L.), in which 
the head has no projecting angles or tubercles, or other 
elevation, but is received usually into the circular cavity 
of the prothorax. 

His third mode of this articulation, that of the Hijmeno- 
ptera and Diptera, is so peculiar, that it ought to be con- 
sidered as a primary kind ; since in this the head moves 
upon the prothorax as upon a pivot, and has a kind of 
versatile motion. 

With regard to his fourth mode, which from his de- 
scription appears to be that of Apoderus Oliv., he allows 
motion to the head only in one direction, observing that 
the lower margin of the prothoracic cavity has a notch. 
But M. Latreille calls the articulation of the head in this 
genus an Enarthrosis a , which admits motion in every di- 
rection ; and if you examine the common species (A. Co- 
ryli), you will find that the prothorax has a sinus taken 
out of its upper margin, as well as out of its lower one — 
which at any rate will allow a motion upwards. 

I merely mention these little inaccuracies, with due 
diffidence, as some apology for giving you a different and 
at least a more popular and general view of this part of 
my subject, which I shall now proceed to state to you. 
It seems to me most convenient for the Entomologist, and 
most consonant to nature, to divide insects, with respect 
to the articulation of the head with the trunk, into three 
primary sections, each admitting one or more subdivi- 
sions. 

a Gen. des Crustac. el Ins, ii. 246. Regne Anim. iii. 325. 



EXTERNAL ANATOMY OF INSECTS. 413 

1 . The first consists of those whose head inosculates 
more or less in the anterior cavity of the chest; and 
whose articulation, therefore, seems to partake in a greater 
or less degree of the ball and socket [Enarthrosis). The 
head, however, is often capable of being protruded from 
this cavity. If you take into your hand any common Har- 
palus that you may find under a stone, you will see, if 
pressed, that it can shoot forth its head, so as to be en- 
tirely disengaged from the prothorax : a neck of ligament 
intervening between them a : of course this power of pro- 
truding the head enables the animal to disengage it at its 
will from the restriction imposed upon its motions by the 
surrounding margin of the prothoracic cavity. To this 
section belong all the Coleoptera, the Heteropterous He- 
miptera (Ci?nexlj., &c), and some of the Neuropttcra [JRa- 
pliidia, Semblis, &c). — It may be further divided into two 
subsections — those, namely, whose head inosculates in 
the prothorax by means of a neck : as for instance La- 
treille's Trachelides, Apoderus, and the Staphylinidce, 
amongst the beetles ; the Reduviadce amongst the Hete- 
ropterous insects, and Raphidia in the Neuroptera ; and 
those whose head inosculates in the prothorax without 
the intervention of a neck ; as, the Petalocera, the aqua- 
tic beetles [Dytiscus, Hydrophilus, &c), and most of the 
genus Curculio L. in the first of these orders, the great 
body of the Cimicidcc in the second, and Semblis, Cory- 
dalis, &c. in the third. 

2. The second section consists of those insects whose 
head does not inosculate in the chest, but is merely sus- 

a This was written directly after the experiment recommended in 
the text had been tried, with the result there stated. 



414 EXTERNAL ANATOMY OF INSECTS. 

pended to it by ligament or membrane. To this belong 
most of the tribes of the Orthoptera Order, with the ex- 
ception of the Mantidce, the Dermaptera, the Homo- 
pterous Hemiptera, and such of the Aptera as have the 
head distinct from the prothorax.— This section admits 
of a triple subdivision : those, namely, whose head is 
wholly covered by the shield of the prothorax, as in 
Blatta L.; those whose head is partly covered by it, as 
Gryllotalpa, and other Gryllina ; and those whose head 
is quite free, not being at all impeded in its motion by 
the prothorax, as the Dermaptera, Nirmus, Pedicu- 
lus, Sec. 

3. The third section consists of those whose head is 
truncated posteriorly, and flat or concave, with a very 
small occipital aperture, and is attached to a neck of the 
prothorax upon which it turns, or is merely suspended 
to that part. This includes the Lepidoptera, Hymeno- 
ptera, Diptera, the Libellulina, &c. in the Neuroptera, 
and the Mantidcc in the Orthoptera. Three subsections 
at least, if not more, present themselves in this section : 
the first is, of those whose head is united to the protho- 
rax, without the latter forming any neck. To this belong 
the Lepidoptera^ Trichoptera P The second is of those 
the upper side of whose thoracic neck is ligamentous ■ 
and here you may range most of the Hymenoptera. The 
third is of those in -whom it is a continuation of the ordi- 
nary integument. In this subsection the Diptera, Libel- 
lulina and Mantidcc will find their place. In this last 
section the head appears to turn upon the thorax as upon 
a pivot. 

Before I finish what I have to say on the articidation 
of the head, I must direct your attention to the analo- 



EXTERNAL ANATOMY OF INSECTS. 415 

gies that hold in this respect between the different tribes. 
Thus the Coleoptera are analogous to the Heteropterous 
Hemijpterct; the Orthoptera, with the exception of the 
Mantidce, to the Homopterous Hemiptera ; the Mantidce 
to the Libellulina ,- the Lepidoptera to the Trichoptera ,- 
the Hymenoptera to the Diptera, with a slight variation, 
and probably others might be traced. 

viii. A word or two upon the motions of which the 
head of insects is capable. M. Cuvier, in the extracts 
lately laid before you, speaks of different powers of move- 
ment as the result of different configurations of the parts 
of the head. This probably is correct with regard to 
many cases ; but a great deal will depend upon the power 
the insect has of protruding its head and disengaging 
its base from the restriction of the prothorax ; for where, 
like the Harpali, Staphylini, &c. it is able to do this, it 
can probably move its head in every direction. It is 
only where the ligaments are less elastic, or allow of lit- 
tle tension, that its movements are confined; and few 
living insects have been sufficiently examined to ascer- 
tain how far this takes place. In those cases belonging 
to the third section of articulations, in which the head 
moves upon the thorax as upon a pivot, as is the case 
with Hymenoptera and Diptera, the movement is nearly 
versatile. I have seen a fly turn its head completely 
round, so that the mouth became supine and the vertex 
prone; and from the form and fixing of the head, it 
should seem that those of the Mantidce were endued 
with the same faculty. 

ix. The parts and appendages of the head are now in 



416 EXTERNAL ANATOMY OF INSECTS. 

the last place to be considered. I shall begin with the 
Mouth, or rather the orifice in which the trophi or organs 
of manducation are inserted. In some insects, as was be- 
fore observed, they occupy all the under-side of the head, 
as in the Arachnida, Myriapoda, &c; but in the great 
majority they fill an orifice in its anterior part, which in 
some instances, as in Lampyris, the Lepidoptera, Ci- 
mex L., Truxalis, appears to be nearly under the head ; 
but in general it terminates that part, though it extends 
further below than above. In Chermcs, a Homopterous 
genus, the promuscis is stated to be in the Antepectus, and 
consequently the mouth ; but, as I shall endeavour to prove 
to you hereafter, this is a fallacy. In the males of the 
species of Coccus there is no mouth at all. In that of the 
elm (C. Ulmi) in lieu there are ten little shining points, 
arranged two before and two behind in a line, and three 
on each side in a triangle 1 . It is to be observed that the 
orifice of which I am speaking is usually much smaller 
in those insects which take their food by suction, the 
Hemiptcra, Lepidoptera, Diptera, &c, than in the mas- 
ticating tribes. With regard to the real mouth, or that 
through which the food enters, I have nothing at present 
to observe, except that it lies between the upper-lip and 
tongue, is sometimes covered by a valve, as in Apis, 
Vespa b , &c, and is different in the masticators and 
suckers. 

I shall next offer a few observations seriatim, as they 
stand in the Table, upon the organs of manducation ; 
which, to avoid circumlocution, instead of Instruvienta 

a Reaum. iv. 40. Latreille Fourmis, 328--. h Plate VII. Fig. 2. k". 



EXTERNAL ANATOMY OF INSECTS. 417 

cibaria, the name Fabricius gave them, I shall call tropin 
or feeders. It is upon these parts, you are aware, that 
the system of the celebrated Entomologist just mentioned 
is founded; and could they always, or even for the most 
part, be inspected with ease, they would no doubt afford 
characters as various and discriminative as those of the 
vertebrate animals. Differences in these parts indicate 
a difference in the mode in which the animal takes its 
food, and often in the kind of food, and sometimes in its 
general economy and habits, — circumstances which are 
powerful and weighty in supporting the claim of any set 
of animals to be considered as forming; a natural genus 
or group. Trifling variations, however, of these parts, 
unless supported by other characters and qualities, ought 
not to have much stress laid upon them, since, if we in- 
sist upon these, in some tribes almost every species might 
be made a genus. 

With respect to their trophi in general, insects of late 
have been divided into two great tribes a , masticators and 
suckers j t\\e.Jlrst including those that are furnished with 
instruments to separate and masticate their food; namely, 
an upper- and under-lip (lahrum and labium), upper- and 
under-jaws {niandibula and maxillce), labial and maxil- 
lary palpi, and a tongue {lingua) : and the second those 
in which these parts are replaced by an articulate or ex- 
articulate machine, consisting of several parts and pieces 
analogous to the above, which pierce the food of the ani- 
mal, and form a tube by which it -sucks its juices. If, 
however, the mode in which insects take their food be 

» Clairville {Ent. Helvet. i. 44) appears to have been the first \vh© 
classed insects according to their mode of taking their food. 
VOL. III. 2 E 



418 EXTERNAL ANATOMY OF INSECTS. 

strictly considered, it will be found that in this view they 
ought rather to be regarded as forming three tribes ; for 
the great majority of the Hymenoptera order, and per- 
haps some others, though furnished with mandibles and 
maxilla?, never use them for mastication, but really lap 
their food with their tongue : these, therefore, might be 
denominated lappets. 

When a mouth is furnished with the seven ordinary 
organs used in taking the food and preparing it for de- 
glutition — I mean the upper-lip and the two upper-jaws ; 
the under-lip and the two under-jaws, including the la- 
bial and maxillary palpi; and the tongue — I denominate 
it a perfect mouth ,- but when it is deficient in any of these 
organs, or they exist merely as rudiments, or when their 
place is supplied by others, (which, though they may be 
analogous parts, have little or no connection with them 
in their use or structure,) I denominate it an imperfect 
mouth. This last I would further distinguish, according 
to the nature of its trophi, by other and more distinctive 
terms, as I shall presently explain to you. 

1. Labrum*. — I shall first consider the organs pre- 
sent in a perfect mouth, beginning with the upper-lip [la- 
bruin). This part, which Fabricius sometimes confound- 
ed with the nose, miscalling it clypeus, is usually a move- 
able b piece, attached by its base to the anterior margin 
of the part last named, and covering the mouth, and 
sometimes the mandibles, from above. In insects in 
their last state it is usually of a horny or shelly substance; 
yet in some cases, as in Copris and Cetonia, beetles that 

a Plate VI. VII. XXVI, a'. 

b In Luc-anus, Lamprina, &c. the labrum seems to form the under- 
side of the nose, and to be connate with it. 



EXTERNAL ANATOMY OF INSECTS. 419 

imbibe juices, it is membranous. In form and shape it 
varies greatly, being sometimes nearly square, at others 
almost round ; in some insects representing a parallelo- 
gram, in others a triangle, and in many it is oblong. In 
some instances it is long and narrow, but more generally 
short and wide. It is often large, but occasionally very 
minute. In the majority it has an intire margin, but it is 
not seldom emarginate or bilobed, or even dentate. Its 
surface is commonly even, but it is sometimes uneven, 
sometimes flat, at others convex, and in a few species 
armed with a short horn or tubercle a . As to itspubescencei 
it is often naked, but now and then fringed or clothed 
with down or hairs, or sprinkled with bristles. It con- 
sists in almost every instance of a single piece ; but an 
exception to this occurs in Halictus, a little bee, in the 
females of which it is furnished with a slender appen- 
dage b . — The direction of the upper-lip is various. It is 
rarely horizontal, or in the same line with the nose, often 
vertical ; it sometimes forms an obtuse angle with the 
anterior part of the head, and occasionally an acute one, 
when it is more or less indexed. The use of this part is 
ordinarily to close the mouth from above, to assist in re- 
taining the food while undergoing the process of masti- 
cation; but in many Hymenopterous insects its principal 
use seems to be, to keep the tropin properly folded ; and 
in some cases where it is inflexed, as in the leaf-cutter 
bees (Megachile Latr.), to defend its base, while the man- 
dibles are employed, from injury by their action c . 

a Kirby Mm. Ap. Angl. i. t. v. Apis *. b.f. 18. b. 
" Ibid. t. ii. Melitta **. b.f 4, 5. Plate XXVI. Fig. 30. 
c Plate XXVI. Fig. 31. Mori. Ap. Angl i. t. x. Apis **. c. 2. 5. 
/. 13, c. 

2 E 2 



420 EXTERNAL ANATOMY OF INSECTS. 

2. Labium*. — On the under-side of the head, and op- 
posed to the upper-lip, the mouth is closed by another 
moveable organ, concerning the nomenclature and ana- 
logies of which Entomologists have differed considerably. 
At the first view of it, this organ seems a very com- 
plex machine, since the under-jaws or maxillce are at- 
tached to it on each side, and the tongue is often seen to 
emerge from it above, so as to appear merely a part of it; 
but as the former answer to the upper-jaws, and the lat- 
ter is the analogue of the part bearing the same name in 
.the vertebrate animals, I shall consider these as distinct 
and primary organs, and treat of the under-lip {labium) 
of which I am now speaking, b}^ itself. Linne takes no 
notice of this part, but his illustrious compatriot and co- 
temporary, De Geer, did not so overlook it : he appears 
to consider the whole apparatus, including the maxillce, 
as the labium^; but sometimes he distinguishes the mid- 
dle piece by that name c ; and the tongue, in the case of 
the stag-beetle, he denominates a proboscis (trompe) d . 
In the Hymenoptera he calls this part tongue, under-lip, 
and proboscis : but seems to prefer the last term e . Fa- 
bricius originally regarded the whole middle piece as a 
labium f ; but afterwards (though his definition is not ac- 
curate, since he assigns the palpi to the ligula, which he 
affirms is covered by the labium — circumstances by no 
means universal in Coleoptera) he considers this as con- 
sisting of ligula and labium*. Latreille at first regarded 

a Plates VI. VII. and XXVI. b. 
b De Geer iv. 124. t. iv./. 12 iii. 415. t. xxi./. 4. 
c Ibid. iv. 281—. t. xi./. 7- d Ibid. 329. t. xii./. 3. 

e Ibid. ii. 775— t. xxvi./. 10. b c, b c. 
PMlos. Entojn. 13. b Syst. Eleuth. i. Prsef. iv. 



EXTERNAL ANATOMY OE INSECTS. 42J 

the ligula of Fabricius as the labium, and called the la- 
bium of that author the mentum*', but afterwards he gave 
the name of labium to the whole middle piece of the 
lower apparatus of the mouth — calling the upper piece, 
with Fabricius, the ligula, and retaining the denomina- 
tion of mentum for the lower b . 

If the circumstances of the case are duly considered, 
I think you will be convinced that the term under-lip, 
or labium, should be confined to that part which the 
learned Dane so named. For I would ask, Which is 
the part on the under side of the head that is the anta- 
gonist, if I may so speak, of the upper-lip or labrum ? 
Is it not that organ which, when the mouth is closed, 
meets that part, and in conjunction with it shuts all in ? 
Now in numerous insects, particularly the Lamellicorn 
beetles {Scarabceus and Lucanus L.), this is precisely the 
case. In the Predaceous beetles, indeed, (Cicindela, Ca~ 
rabus, Dytiscus L. &c. ) the under-lip does not meet the 
upper, to close the mouth and shut in the tongue ; nei- 
ther can the tongue be said so to do, but only, from some 
circumstances connected with its manner of taking its 
food, it is requisite that the last-mentioned organ should 
not be retractile or covered ; but its miscalled mentum 
is still the analogue of that part which helps to close the 
mouth in the former tribe. Should not this, therefore, 
which so often performs the office, be distinguished by the 
name, of a lip ? Again, is it not rather incongruous to 
consider that organ which confessedly more or less per- 
forms the office of a tongue, as a part of the lip ? Though 
it often wears that appearance, yet I believe, if the mat- 

- Gen. Crustac. el Ins. i. 180. b N. Diet. d'Hist. Nat. iv. 246. 



422 EXTERNAL ANATOMY OF INSECTS. 

ter is thoroughly and patiently investigated, it w ill be 
found that on their upper side its roots are attached to the 
interior of the upper side of the head, as well as on their 
lower side to the labium ,• so that it may be regarded as 
common to the two lips, and therefore not properly con- 
sidered as an appendage of the under-lip alone. 

Having assigned my reasons for preferring the name 
given to the part in question by Fabricius, rather than 
that of Latreille, I shall next make my observations on 
the part itself. In many cases the labium, or the middle 
piece of the lower oral apparatus, appears to consist oi 
two joints : this you may see in the great water-beetle 
(Ut/drojjkilus piceus), the burying-beetles (Necrojjhorus), 
the Orthopterous tribes a , the Hymenoptera b , and others. 
In this case the upper or terminal piece is to be regarded 
as the labium, and the lower or basal one (which Mr. 
MacLeay calls the stipes) as the mention or chin — at 
other times, as in some Lamellicorn beetles, the only se- 
paration is a transverse elevated line, or an obtuse angle 
formed by the meeting of the two parts, and very fre- 
quently there is no separation at all, in which case the 
whole piece, the mentum merging in it, may be denomi- 
nated the labium. 

With respect to its substance, the labium in most Co- 
leopterous insects is hard and horny, in Necrophorus it 
is membranous, and the mentum harder ; in Prionus 
coriarius, our largest Capricorn-beetle, both are mem- 
branous; in the bee-tribes, Apis L., the labium rather 
resembles leather, while the mentum is hard. Its surface 
is often convex, sometimes plane, and sometimes even 

» Plate VI. Fig. G. b'. a". * PlatS: VII. Fig. 3. b'. a'. 



EXTERNAL ANATOMY OF INSECTS. 423 

concave; as for instance in Melolontha Fullo, a rare 
chafer occasionally found on the coast of Kent. In some 
it is covered with excavated points ; in others it is quite 
smooth. In numbers, as in the Predaceous beetles, both 
labium and mentum are perfectly naked ; in others, as in 
the common cockchafer, they are hairy ; in Geniates bar- 
batus Kirby, another chafer in the male insect, the la- 
bium is naked, while the mentum, which forms a piece 
distinct from that part, is covered with a dense rigid 
beard a . In shape the whole labium varies considerably, 
much more than the labrum ,• for in addition to most of 
the forms I enumerated when I described that organ, 
which I shall not here repeat, you may meet with exam- 
ples of many others. Thus, to instance in the Petalocerous 
tribes (Scarabams L.), in some, as in the Rutelidce, the 
labium is urceolate, or representing in some degree the 
shape of a pitcher b ; in others it is deeply concave, and 
not a little resembles a basin or a bowl c ; this form is 
peculiar to the labium of Cremastocheilus Knoch, a scarce 
North American beetle ; in another related to this, but 
of an African type (Genuchus, Kirby MS. Cetonia cru~ 
enta F.) 3 it is a trapezoid plate, which is elevated from 
the head, and hangs over the throat like a chin d . In the 
Hymeyiojptera it is extremely narrow and long, and em- 
braces the sides of the tongue, as well as covering it from 
below; so that it wears the appearance of a kind of tube e . 
Generally speaking, the length of the labium exceeds its 
breadth ; but in the Predaceous beetles the reverse of 

a Kirby Linn. Trans, xii. t. xxi./. 8./. 

b Ibid. t. xxi./. 10. d. MacLeay Hor, Entomol. i. t. m.f. 26, 27. 
c Plate XXVI. Fig. 35. d Ibid. Fig. 34. 

f Plate VII. Fig. 3. b'. 



424 EXTERNAL ANATOMY OF INSECTS. 

this takes place, it being very short and wide, and usu- 
ally terminating towards the tongue in three lobes or 
teeth which form two sinuses varying in depth a . 

The mentum taken by itself affords no very striking 
characters to which I need call your attention : I shall 
only observe, that in Hymenoptera it is generally of a 
triangular shape b ; but before I proceed to consider the 
labial palpi, it will be proper to notice the remarkable 
labium of Orthopterous insects, and of the Libellulina, 
between which there is no little analogy. At first you 
would imagine the terminal part of this organ in the for- 
mer to be the analogue of the tongue, or ligula F. ; as it 
is indeed generally regarded by modern Entomologists c . 
It seems, like the tongue of the Carabi L., Dj/tisci, &c, to 
be a distinct piece, which has below it both labium and 
mentum; but when you look within the mouth, you will 
find a linguiform organ d , which evidently acts the part 
of a tongue, and therefore ought to have the name ; and 
the piece just alluded to must either be regarded as the 
termination of the lip, or as an external accompaniment 
of the tongue, analogous, it may be, to the paraglossce in 
bees e . In a specimen of Acrida viridissima (Locusta F.) 
which I dissected, the tongue is as long as the appen- 
dage of the under-lip, and by its upper surface seems 
to apply closely to it. In the Libellulina a similar organ 
is discoverable f , which on its upper-side terminates in 
the pharynx, like that of one of the Harpalida before 
mentioned. In the Orthoptera, therefore, I regard the 
labium as consisting of three articulations, the upper one 

* Plate XXVI. Fig. 24. b'. b Plate VII. Fig. 3. a". 

1 N. Diet. d'Hisf. Nat. xxiv. 171. d Plate VI. Fig. 6. e'. 

2 Plate VII. Fig. 3. i". « Plate VI. Fig. 12. e'. 



EXTERNAL ANATOMY OF INSECTS. 425 

divided into two, three, or more lobes a ; the intermediate 
one more directly answering to the labium of other in- 
sects, and the basal one or mentum. This organ in the 
Libellulina is of a different structure : it has only two 
articulations representing labium and mentum; but the 
former consists of three parallel pieces, the two exterior 
ones rising higher than the intermediate one, and at their 
inner angle having an acute sinus from which the palpi 
emerge ; and the intermediate piece, which is longitudi- 
nally channelled, lapping over the inner side of the lateral 
pieces. From the angle of the covered part of these 
pieces, a subulate short horizontal horn points inwards 
towards the tongue, which it must keep from closing 
with the labium^. 

3. Palpi Labiales c . — The last-mentioned organs, the 
labial palpi, next claim our attention ; but before I advert 
particularly to them, it will be proper to premise a few 
words upon palpi, or feelers, in general. These are usual- 
ly jointed moveable organs, of a corneous or coriaceous 
substance, attached by ligaments to the labium and 
maxillae, and in the Crustacea even to the mandibulce. 
Their joints, which are usually more or less obconical, 
articulate also in each other by ligaments, with perhaps 
some little mixture of the ball and socket. Their ends, 
the last joint especially, seem furnished with nervous 
papillce which indicate some peculiar sense, of which they 
are the instrument. What that sense is has not been 
clearly ascertained, and concerning which I shall enter 
more into detail in another place. Their motion seems 

» Plate VI. Fig. 6. b'. b Ibid. Fig. 12. b". 

« Plates VI. VII. XXVI. b". 



426 EXTERNAL ANATOMY OF INSECTS. 

restrained, at least in some, to two directions, towards 
and from the mouth. They were called palpi or feelers, 
because the insect has been supposed to use them in ex- 
ploring substances. There seem to be no organs in the 
vertebrate animals directly analogous to thepalpi of in- 
sects and Crustacea, unless, perhaps, the cirri that emerge 
from the lips of some fishes, as the cod, red mullet, &c. 
which Linne defines as used in exploring (prcetentantes). 
Whether the vibrissas, miscalled smellers, of some quadru- 
peds and birds have any reference to them, I will not 
venture to affirm ; but the feline tribe evidently use their 
bristles as explorers, and they are planted chiefly in the 
vicinity of the mouth. 

Having made these general remarks, I shall now con- 
fine myself to the labial palpi. I call them labial palpi, 
because that term is in general use, and because in many 
cases they really do emerge from what I consider as the 
labium, as in most of the chafers; but they might with 
equal propriety be denominated lingual palpi, since they 
sometimes appear to emerge from the tongue (as in the 
stag-beetle {Lucaniis Cervus). In some instances, as in 
the Predaceous beetles, they seem to be common to both 
labium and tongue, being attached at their base on the 
upper side to the former, and on the under side to the 
latter. As to their situation : they emerge from the base 
of the labium in the locusts [Locusta Leach) a ; from its 
middle in Hister maximus h \ from its summit in Amblyte- 
rus MacLeay c ; and from its lateral margin in Di/nas- 
tes MacLeay, &c. They consist of from one to Jour 



a Plate VI. Fig. 6. b". b Hor. Entomolog, 1. 1. \.f. l.g. 

c Ibid.t.ilf. 18. g. 



EXTERNAL ANATOMY OF INSECTS. 427 

joints ; which, I believe, they never exceed. They vary 
in length ; though generally shorter than the maxillary 
palpi, yet in the ferocious tiger-beetles (Cicindela L.) 
they equal them in length ; and in the hive-bee and hum- 
ble-bees, and many other bees, they are considerably 
longer a . The two first joints of these palpi, however, 
in these bees are different in their structure from the two 
last, being compressed and flat, or concave; and the two 
last joints, instead of articulating with the apex of the 
second, emerge from it below the apex : so that these 
two first joints seem rather elevators of the palpi than 
really parts of them b . With respect to the relative pro- 
portions of their joints to each other : in some cases the 
first joint is the longest and thickest, the rest growing 
gradually shorter and smaller c ; in others, the second is 
the longest d ; mothers, again, the third e , and sometimes 
the last f ; and often all are nearly of the same size and 
lengths. They are more commonly naked, but some- 
times either generally or partially hairy. Thus in Cicin- 
dela, the last joint but one is usually planted with long 
snow-white bristles in a double series, while the rest of 
the joints have none; and in Copris Latr. all of them are 
extremely hairy. In shape they do not vary so much as 
the maxillary palpi, being most frequently filiform or 
subclavate, and sometimes setaceous; the last joint varies 
more in shape than the rest, and is often remarkably 



a Kirby Mon. Ap. Angl. i. t. xii. neuLf, l.g. e. 

b Ibid. 93. 103—. t. vi A pis **. b. /. 3. b c. 

c Ibid. t. i. *. a./. 3. b A Ibid. t. ix. Apis **. c. 2. y.f. 3. b. 

* Clairv. Ent. Helvet. h /. xxiv.f. 1. c. 

i Plate XXVL Fig. 24, 28. b". 

s Mon. Ap. Angl. i. t. ii. Militia ••. b.f. 2. c. 



4-'28 EXTERNAL ANATOMY OF INSECTS. 

large, triangular, and shaped like the head of a hatchet- 1 ; 
and at others it resembles the moon in her first quar- 
ter 5 . In the great dragon-fly, or demoiselle if you pre- 
fer the gentler French name {JEshna F.) the labial palpi, 
which are without any visible joints, are terminated by a 
minute mucro or point c . With regard to their direction 
and flexure, they frequently, as in the instance just men- 
tioned, turn towards each other, and lie horizontally upon 
the end of the labium. Sometimes, as in the Cicindelidte, 
they appear to point towards the tail of the insect, the last 
joint rising, and forming an angle with the rest of the 
feeler. In other instances they diverge laterally from the 
labium, the last joint turning again towards it at a very 
obtuse angle. 

4. Mandibulce d . — Having considered the analogues of 
the lips in our little beings, I must next call your atten- 
tion to the representatives of the jaws. The vertebrate 
animals, you know, are mostly furnished with a single 
pair of jaws, one above and the other below, in which the 
teeth are planted and which have a vertical motion. But 
insects are furnished with two pair of jaws, a pair of 
upper-jaws and a pair of under-jaws, which have no 
teeth planted in them, and the motion of which is hori- 
zontal. — I shall begin with an account of the upper-jaws. 
These by modern Entomologists, after Fabricius, are de- 



a Plate XIII. Fig. 2. Linn. Trans, xii. t. xxi./. 6. b. 

b This is the case with Oxyporus F. Plate XIII. Fig. 4. 

c Plate VI. Fig. 12. b". Latreille, N. Diet. d'Hist. Nat. xvii. 
545, seems not to regard these as palpi; but from their tubular form, 
and insertion in the socket of the labium, it is clear that they ought 
to be so considered. <J Plates VI. VII. XXVI. c'. 



EXTERNAL ANATOMY OF INSECTS. 429 

nominated mandibles (mandibulce) : a term appropriated 
by Linne to the beaks of birds. The upper-jaws of in- 
sects this great naturalist named maxilla; — and not im- 
properly, since the office of mastication is more pecu- 
liarly their office than that of the under-jaws, which Fa- 
bricius has distinguished by that name : as the term man- 
dible, however, is generally adopted, I shall not attempt 
to disturb it. 

The mandibles close the mouth on each side under the 
labrum or upper-lip. They are generally powerful or- 
gans, of a hard substance like horn; but in the Lamellicorn 
beetles of Mr. MacLeay's families of Scarabceidce and Ce- 
toniadce, they are soft, membranous, and unapt for masti- 
cation. In Coleopterous insects they commonly articulate 
with the head by means of certain apophyses or processes, 
of which in many cases there are three discoverable at 
the exterior base of the mandibles ; one, namely, at each 
angle, and one in the middle. That on the lower side is 
usually the most prominent, and wears the appearance 
of the condyle of a bone : it is received by a correspond- 
ing deep socket (or cotyloid cavity) of the cheek, in 
which, being perfectly smooth and lubricous, it moves 
readily, but without synovia, like a rotula in its aceta- 
bulum. The upper one projects from the jaw, forms 
the segment of a circle, and is concave also on its inner 
face. A corresponding more shallow, or, as anatomists 
speak, glenoid cavity of the cheek, where it meets the 
upper-lip, receives it, and the concave part admits a lubri- 
cous ball projecting from the cheek, upon which it turns a . 

;l A corresponding articulation takes place between the tibia and 
thio-h of some of the Scarabceidce, which will be hereafter described, 
See Plate XXVII. Fig. 8— 1 1. 



430 EXTERNAL ANATOMY OF INSECTS. 

This structure you will find in the stag-beetle, and some 
other timber-devourers. Other Coleoptera have only a 
process of a similar structure at each of the dorsal angles 
of the base of the mandible, the intermediate one being 
wanting ; and the articulation does not materially differ, 
as far as I have examined them, in the Hymenoptera and 
Neuroptera. In the Orthoptcra, the structure approaches 
more nearly to that of the stag-beetle, since there are 
three prominences : it is thus well described by M. Mar- 
cel de Serres: " This articulation," says he, "takes place 
in two ways. At first, in the upper surface of the man- 
dible, and at its base, may be observed two small promi- 
nences and a glenoid cavity ; these prominences are re- 
ceived in two glenoid cavities excavated in the shell of 
the front, as the cavity of the mandible receives a small 
prominence of the same part. Below the mandible, and 
at its base, there is a kind of condyle, which has its play 
in a cotyloid cavity excavated in the shell of the temple, 
far below the eye, and at the extremity of the coriaceous 
integument of the head 3 ." Within the head in this or- 
der, at least in Locusta Leach, is a vertical septum which 
divides the head into two chambers, as it were, an occi- 
pital and a frontal, consisting of a concave triangular 
stem, terminating in two narrower concave triangular 
branches, so as to resemble the letter Y, and forming 
three openings, an upper triangular one, and two lateral 
subquadrangular ones, which last are the cavities that re- 
ceive the base of the mandibles. This partition, which I 
would name Cephalophragma, doubtless affords a point of 
attachment to many of the muscles of the head. It does 

a Comparaison des Organes de la Mastication des Orthoptics, 2. 



EXTERNAL ANATOMY OF INSECTS. 431 

not appear to have been noticed, unless it be synonymous 
with the intermaxillary arcade of Marcel de Serres a . 
Probably a corresponding support to the muscles, &c. 
may exist, as we have seen it does in Vespa L. b , in many 
other heads of the different Orders, which have not yet 
fallen under examination. Many mandibles, as those of 
the hornet &c, appear to be suspended to the cavity of 
the head on the inside by a marginal ligament suffi- 
ciently relaxed to admit of their play : those of the Or- 
tlioptera, M. Marcel de Serres informs us, are united to 
the head by means of two cartilages, the outermost being 
much the shortest, to which their moving muscles are 
attached. These he considers as prolongations of the 
substance of the mandible c . The bottom of mandibles, 
when cleared of the muscles &c, inclines almost univer- 
sally to a triangular form ; but in some cases, as in the 
stag-beetle, it is nearly a trapezium. I cannot conclude 
this subject without noticing the motions of the mandi- 
bles. What the author lately quoted has said with re- 
gard to those of the Orthoptera, will, I believe, apply 
equally well to all the mandibulate orders. " The arti- 
culation of mandibles with the skull appears to take place 
by two points solely ; and as these parts only execute 
movements limited to a certain direction, they may be 
referred to ginglymus d . — The movements of mandibles 
are limited to those from within outwards, and from 
without inwards e ." Whether they are restricted from 
any degree of vertical motion, has not yet been proved, 
as the jaws of vertebrate animals move horizontally as 

A Comparaison des Organcs de la Mastication des Orthopteres, 2. 
b Sec above, p. 407- note b. c Ubi supra, 4. d Ibid. e Ibid. 5. 



432 EXTERNAL ANATOMY OF INSECTS. 

well as vertically — so those of insects may have some 
motion vertically as well as horizontally ; and it seems 
necessary for some of their operations that they should. 
I am not anatomist enough to speak with confidence on 
the subject, but the ball and socket articulation at the 
low r er part of the mandible, and the curving one at the 
upper, though a kind of ginglymus, seems to imply a de- 
gree of rotatory movement, however slight. 

I must next say something upon the general shape of 
these organs. Almost universally they incline to a tri- 
quetrous or three-sided figure, with their external sur- 
face convex, sometimes partially so, and their internal 
concave. Most frequently they are arched, curving in- 
wards ; but sometimes, as in Prionus octangularis*, a Ca- 
pricorn beetle, and others of that genus, they are nearly 
straight; and in Rhina barbirostris b i a most remarkable 
Brazilian weevil, their curvature is outwards. In Pholi- 
dotus lepidotus MacLeay, and Lucanus JElephas, two in- 
sects of the stag-beetle tribe, they are bent downwards ; 
and in Lucanus nebidosus K. (Myssonotus MacLeay) they 
turn upwards c . They are usually widest at the base, 
and gi'ow gradually more slender to the apex, but in the 
hornet ( Vespa Crabro) the reverse takes place, and they 
increase in width from the base to the apex; and in the 
hive-bee, and others of that tribe, they are dilated both 
at base and apex, being narrowest in the middle ; others 
are nearly of the same width every where. In those 
insects that use their mandibles principally for purposes 
connected with their economy, they are often more broad 

a Oliv. Ins, no. 66. Prionus. t. xiii.y. 54. 
b Ibid. no. S3. Curculio. t. Vf.f. 37- 
c Linn. Trans, xii, /. xxi.f. 12. 



EXTERNAL ANATOMY OF INSECTS. 433 

in proportion to their thickness, than they are in those 
which use them principally for mastication. In the lo- 
cust tribes [Locusta Leach), they are extremely thick 
and powerful organs, and fitted for their work of devas- 
tation ; but in the glow-worm (Lampyris), they are very 
slender and minute. In those brilliant beetles, the Bu- 
prestes, they are very short ; but in the stag-beetles, and 
those giants in the Capricorn tribe, the Prioni, they are 
often very long a . They either meet at the summit, lap 
over each other, cross each other, or are protended 
straight from the head ; as you have doubtless observed 
in the stag-beetle, whose terrific horns are mandibles of 
this description. These organs are usually symmetrical, 
but in some instances they are not : thus in Hister Icbvus, 
a kind of dung-beetle, the left hand mandible is longer 
than the right; in Creophilus maxillosus K. (Staphy- 
linus L.), a common rove-beetle, in the left hand man- 
dible the tooth in the middle is bifid, and in the right 
hand one intire ; and in Bolbocerus K. the mandible of 
one side, in some species the dexter, and in others the 
sinister, has two teeth, and the other none. 

The next circumstance with respect to these organs 
which demands our attention, is the teeth with which 
they are armed. These are merely processes of the sub- 
stance of the mandible, and not planted in it by gompho- 
sis b , as anatomists speak, as they are in vertebrate ani- 
mals. They have, however, in their interior, at the base 

a For Maudibles of Locusta see Plate VI. Fig. 6. c'. of Lampyris 
Oliv. Ins. no. 28. t. If. 1 of Buprestis, Ibid. no. V>2. t. iii./. 17- of 
Lucanus, Ibid. no. 1. 1. i— v. and of Prionus, Ibid. no. 60. t. ii./. 8. 

b Gomphosis is, when one bone is immoveably fixed in another as 
a nail in a board. 

VOL. III. 2 F 



434 EXTERNAL ANATOMY OF INSECTS. 

at least, in the Orfhoptera, a coriaceous lamina that se- 
parates them in some sort from the body of the mandi- 
ble a . Many insects, however, have mandibles without 
teeth ; some merely tapering to a sharp point, others ob- 
tuse at the end, and others truncated b . Of those that 
have teeth, some have them on the inside at the base, as 
Manticora, an African tiger-beetle c ; others in the mid- 
dle, as StaphyMnus olens, a rove-beetle, Lethrus cepha- 
lotes, &c. d ; others at the end, as many weevils [Curcu- 
lio L.) e ; others again on the back, as the Rutelidce, a tribe 
of chafers f , and Lethrus, a beetle just named; others 
once more on the lower side of the base, in the form 
of a tooth or spine, as in Melitta spinigera, a species of 
wild-bee, and some of its affinities ? ; and lastly, others 
on the upper side of the base in the form of a long tor- 
tuous horn, as in that singular wasp Synagris cornuta F. 
before noticed as a sexual character h . In the stag- 
beetle tribes (LucanuslL.) these teeth are often elongated 
into short lateral branches, or a terminal fork ! . They 
are sometimes truncated, sometimes obtuse, and some- 
times acute. 

But with regard to their land, it will be best to adopt 
the ideas of M. Marcel de Serres ; for though his re- 
marks are confined to the Orfhoptera, they may be ap- 
plied with advantage to the teeth that arm the mandibles 

a Marcel de Serres ubi supra. 7. 

b See Plate XIII. Fig. 7- Kirby Mon. Ap. Angl. i. t. xiii./. 13. 
and t. xii. neut.f. 10. c p LATE XXVI. Fig. 19. 

d Oliv. Ins. no. 42. t. If. 1. and no. 2. t. If. 1. b. 
e Plate XXV7. Fig. 1 6, 18. f Ibid. Fig. 21 . 

g Mon. Ap. Angl. i. t. iv. Melitta. f. 5—8. 
h Drury Ins. ii. t. xlviii./. 3. See above, p. 315. 
1 Oliv. no. 1. t. v.f 16. &c. t. in.f. 7. 



EXTERNAL ANATOMY OF INSECTS. 435 

of insects in general. He perceives an analogy between 
those of this Order and the teeth of quadrupeds ; and 
therefore divides them into incisive or cutting, laniary 
or canine, and molary or grinding teeth. He denomi- 
nates those incisives that are broad, having in some de- 
gree the shape of a wedge, their external surface being 
convex, and their internal concave ; whence they are evi- 
dently formed for cutting. The laniaries are those which 
have a conical shape, are often very acute, and in gene- 
ral the longest of any ; and in some insects, as the carni- 
vorous Orthoptera (and the Libellulina), they cross each 
other. The molaries are the largest of all, and their 
purpose is evidently to grind the food. There is never 
only a single one to each mandible, while the number of 
the incisives and laniaries is very variable. As the mo- 
laries act the principal part in mastication, they are 
nearer the inner base of the mandible or point of sup- 
port : they serve to grind the food, which has been first 
divided by the incisives or torn by the laniaries. The 
carnivorous tribes are destitute of them ; in the omnivo- 
rous ones they are very small, and in the herbivorous 
ones they are very large a . So that in some measure 
you may conjecture the food of the animal from the teeth 
that arm its mandibles. Of incisive teeth you may find 
an example in those that arm the end of the mandibles 
of most grasshoppers (Locusta), and of the leaf-cutter- 
bees (Megachile Latr.) b ; of the laniary or canine teeth, 
you will find good examples in the mandibles of the 
dragon-flies (Libellulina); the two external teeth of the 



a Comparaison des Organes, &c. 7 — • 

b Plate VI. Fig, 6. and XIII. Fig. 5. a'". 

2 F 2 



436 EXTERNAL ANATOMY OF INSECTS. 

apex of those of the leaf-cutter bees may be regarded as 
between the incisives and laniaries ; and the pointed man- 
dibles without teeth may be deemed as terminating in a 
laniary one a . The lower part of the inner or concave 
surface of the mandibles of grasshoppers will supply you 
with instances of the molary teeth, and the apex, also, of 
those of some weevils, as Curculio Hancocki K. b But 
the most remarkable example of a molary organ is exhi- 
bited by many of the Lamellicorn beetles, especially those 
that feed upon vegetables, whether flower or leaf. — 
Knoch, who indeed was the first who proposed calling 
mandibles according to their teeth, incisive, laniary, or 
molary, but who does not explain his system clearly, 
observed that the mandibles of some Melolonthae have a 
projection with transverse, deep furrows, resembling a 
file, for the purpose of bruising the leaves they feed upon c : 
and M. Cuvier, long after, observed that the larvse of 
the stag-beetle have towards their base a flat, striated, 
molary surface ; though he does not appear to have no- 
ticed it in any perfect insect d . This structure, with the 
exception of the Scarabceidce and Cctoniadce, seems to 
extend very generally through the above tribe; since it 
may be traced even in Geotricpes, the common dung- 



a Plate VI. Fig. 12. and XIII. Fig. 5. b'". 

b Plate XXVI. Fig. 16. 

c I was not aware that Knoch had observed this part, till some 
time after the publication of my paper On Mr. William MacLeay's 
Doctrine of Affinity and Analogy (see Linn. Trans, xiv. 105 — ), when 
I happened to meet with it in a letter from a friend, received more 
than thirteen years ago; but without any reference to the work of 
Knoch, in which it was stated. It was doubtless taken from his 
Beitrage zur Insehtengeschichte. 

d Anat. Comp. hi. 321 — . 



EXTERNAL ANATOMY OF INSECTS. 437 

chafer, in which at the base of one mandible is a con- 
cave molary surface, and in the other a convex one, but 
without any furrows : a circumstance that often distin- 
guishes those that have furrows. — In the Dynastidce 
the affinity of structure with the Melolonthida &c. is 
more pronounced, the furrows to which ridges in the 
other mandible correspond being reduced to one or two 
wide and deep ones ; whereas in some of the latter tribe 
they are very numerous. These mandibles, in many 
cases, at their apex are furnished with incisive teeth to 
cut off their food, and with miniature mill-stones to 
grind it a . The part here alluded to I call the Mola. 

Were I to ask you what your idea is with regard to 
the use of the organs we are considering, you would 
perhaps reply without hesitation, " Of what possible use 
can the jaws of insects be but to masticate their food?" 
But in this you would in many instances be much mis- 
taken ; as you will own directly if you only look at the 
mandibles of the stag-beetle — these protended and for- 
midable weapons, as well as those of several other bee- 
tles, cannot be thus employed. " Of what other use, 
then, can they be?" you will say. In the particular in- 
stance here named, their use, independent of mastica- 
tion, has not been satisfactorily ascertained; but in many 
other cases it has. Recollect, for instance, what I told 
you in a former letter, of those larvae that use their un- 
guiform mandibles as instruments of motion b . Again : 
amongst the Hymenopterous tribes, whose industry and 
varied economy have so often amused and interested you, 

a One of these mandibles is represented in Plate XXVI. Fig. 
20. a'", incisive teeth d'". molary plate. Comp. Linn. Trans, ubi 
sapr. t. iii./. 4. c a b. b Vol. II. p. 275—. 



438 EXTERNAL ANATOMY OF INSECTS. 

many have no other tools to aid them in their various 
labours and mechanical arts : to some they supply the 
place of trowels, spades, and pick-axes ; to others that of 
saws, scissors, and knives — with many other uses that 
might be named. In fact, with the insects of this intire 
Order mastication seems merely a secondary, if it is at 
any time their use. Still comprehending in one view all 
the mandibulate Orders, though some use their mandi- 
bles especially for purposes connected with their economy, 
yet their most general and primary use is the division, 
laceration, and mastication of their food ; and this more 
exclusively than can be affirmed of the under-jaws (max- 
illa:). This will appear evident to you, when you consi- 
der that insects in their larva state, in which universally 
their primary business is feeding, with very few excep- 
tions use the organs in question for the purpose of masti- 
cation, even in tribes, as the Lepidoptera, that have only 
rudiments of them in their perfect state — while the ?nax- 
illde ordinarily are altogether unapt for such use. The 
exceptions I have just alluded to are chiefly confined to 
the instance of suctorious mandibles; or those which, 
being furnished at the end with an orifice, the animal in- 
serting them into its prey, imbibes their juices through 
it. This is the case with the larvae of some Dytisci, He- 
mefobius, and Myrmeleon* ; and spiders have a similar 
opening in the claw of their mandibles, which is sup- 
posed to instil venom into their prey b . 

Under this head I must not pass without notice an 
appendage of the mandibles, to be found in some of the 

a In the Myrmeleon, or ant-lion, the suction is promoted by the 
action of a piston, that pumps up the juices. Reaum. vi. 3G9. 
h De Geer iv. 380'—. t. xv./. 10. See above, p. 121. 



EXTERNAL ANATOMY OF INSECTS. 439 

rove-beetles (Staphylinidce), as in Ocypus, Staphylinus, 
and Creophilas Kirby. In the first of these it is a curved, 
narrow, white, subdiaphanous, submembranous, or rather 
cartilaginous piece, proceeding from the upper side of 
the base of the mandible a ; in the second it is broader, 
straighter, and fringed internally and at the end with 
hairs ; and in this at first it wears the appearance of be- 
ing attached laterally to the mandible under the tooth b , 
but if closely examined, you will find that it is separate : 
in Creophilns maxillosus it is broader. This is the part 
I have named prostheca. It is perhaps useful in prevent- 
ing the food from working out upwards during mastica- 
tion. 

5. Maxilla; c . The antagonist organs to the mandible 
in the lower side of the head, are the under-jaws, or max- 
illa — so denominated by the illustrious Entomologist of 
Kiel. Linne appears to have overlooked them, except 
in the case of his genus Apis, in which he regards them, 
and properly, as the sheath of the tongue. De Geer 
looked upon them in general as part of the apparatus of 
the under-lip or labium; and such in fact they are, as 
will appear when we consider them more particularly. 
Fabricius has founded his system for the most part upon 
these organs, the principal diagnostic of ten out of his 
thirteen Classes (properly Orders) being taken from them; 
and in the modern, which may be termed the eclectic, sy- 
stem, although the Orders are not founded upon them, 
yet the characters of genera, and sometimes of large 
tribes, are derived from them : and as they appear less 

» Plate XIII. Fig. 7. c". 

b Oliv. Ins. no. 42. Staphyl'mus. t. i.f. 1. b. 

c Plates VI. VII. XXVI. tl'. 



4-40 EXTERNAL ANATOMY OF INSECTS. 

liable to variation than almost any other organ, as Mr. 
W. S. MacLeay has judiciously observed, there seems 
good reason for employing them — it is therefore of im- 
portance that you should be well acquainted with them. 
Their situation is usually below each mandible, on each 
side of the labium; towards which they are often some- 
what inclined, so that their tips meet when closed. In 
some cases, as in the Predaceous beetles (CarabusJa. &c), 
they exactly correspond with the mandibles; but in others 
their direction with respect to the head is more longitu- 
dinal, as in the Hymenoptera, &c. In substance they 
may be generally stated to be less hard than those or- 
gans ; yet in some instances, as in the JLibellidina, Ano- 
plognathidcc, &c. they vie with them, and in the Scara- 
baeidai and Cetoniada? exceed them, in hardness. In the 
bees, and many other Hymenoptera, they are soft and 
leathery. Their articulation is usually by means of the 
hinge on which they sit : it appears entirely ligamentous, 
and they are probably attached to the labium at the 
base, or mentum — at least this is evidently the case with 
the Hymenoptera, in which the opening of the maxillae 
pushes forth the labium and its apparatus. In that re- 
markable genus related to the glow-worms, now called 
Phengodes {JLampyris plumosa F.), and in the case-worm 
flies (Tric/wptera K.), the maxilla; appear to be connate 
with the labium, or at least at their base. — As to their 
composition, these organs consist of several pieces or por- 
tions. At their base they articulate with a piece more 
or less triangular, which I call the hinge (Cardo) z . This 
on its inner side is often elongated towards the interior 

a Plate VI. Fig. 3, 6, 12. VII. Fig. 3. e". 



EXTERNAL ANATOMY OF INSECTS. 44*1 

of the base of the labium, to which it is, as I have just 
observed, probably attached. This elongate process of 
the hinge in Apis, Bombus, &c. appears a separate arti- 
culation ; and the two together form an angle upon which 
the mentum sits a , and by this the maxilla acts upon the 
labial apparatus. 

The next piece is the stipes or stalk of the maxilla. 
This is the part that articulates with the hinge, and may 
be regarded in some cases, as in the Orthoptera &c, as 
the whole of the maxilla below the feeler; and in others, 
as in the Geotrupidce, Staphylinidce &c, as only the back 
of it, the inside forming the lower lobe. This piece is 
often harder and more corneous than the terminal part, 
is linear, often longitudinally angular, and in the bee- 
tribes [Apis L.) is remarkable on its inner side for a se- 
ries of bristles parallel to each other like the teeth of a 
comb b . In Pogonophorus Latr., a kind of dor or clock- 
beetle, it is armed on the back with four jointed spines, 
the intermediate one being forked c . M. Latreille has 
thus described the stipes of the maxilla of Coleoptera : 
" Next comes the stalk," says he, " which consists of 
three parts : one occupies the back and bears the feeler ; 
the second forms the middle of the anterior face, and its 
figure is triangular; the third fills the posterior space 
comprised between the two preceding ; and is that which 
is of most consequence in the use of the maxilla; the an- 
terior feeler, where there are two, the galea, and the 
other appendages that are of service in deglutition, are 
part of that piece d ." 

a Plate VII. Fig. 3. a", e". Mon. Ap. Angl. i. t. xiii./. 1. <?. 

b Ibid.f. 3. a. c Clairv. Ent. Helvet. ii. 146. t. xxiii./. super, b. 

A N. Diet. d'Hist. Nat. iv. 243. 



442 EXTERNAL ANATOMY OF INSECTS. 

The third and terminal portion of the maxilla is formed 
by the lobe, or lobes (Lobi). This may be called the 
most important part of the organ, since it is that which 
often acts upon the food, when preparing for degluti- 
tion. When armed with teeth or spines at the end, 
its substance is as hard as that of the mandibles ; but 
when not so circumstanced, it is usually softer, re- 
sembling leather, or even membrane a ; and sometimes 
the middle part is coriaceous, and the margin membra- 
nous. This part is either simple, consisting only of one 
lobe, as you will find to be the case with the Hymeno- 
piera, Dynastidce, Nemognatha, and several other bee- 
tles; or it is compound, consisting of too lobes. In the 
former case, the lobe is sometimes very long, as in the 
bee tribes, and the singular genus of beetles mentioned 
above b , Nemognatha; and at others very short, as in 
Hister, &c. The bilobed maxilla? present several diffe- 
rent types of form. Nearest to those with one lobe are 
those whose lower lobe is attached longitudinally to the 
inner side of the stalk of the organ, above which it 
scarcely rises. Of this description is the maxilla in the 
common dung-beetle (Geotrupes stercorarius), and rove- 
beetle {Staphylinus olens). c Another kind of formation 
is where the lower lobe is only a little shorter than the 
upper : this occurs in a kind of chafer (Macraspis tetra- 
dactyla MacLeay). d A third is where the upper lobe 
covers the lower as a shield ; as you will find in the Or- 



a |n Anoplognathus, however, though it has neither teeth nor 
spines^ it is as hard as the mandibles. 
b . See above, p. 317- 
'«• 'Plate XXVI. Fig. 10, 11. d'". e"\ 
J Ibid. Fig. 9. d". e"\ 



EXTERNAL ANATOMY OF INSECTS. 44-3 

thoptcra order, and the Libellulina, and almost in Meloe*. 
A fourth form is where the upper lobe somewhat resem- 
bles the galeate maxilla just named; but consists of two 
joints. This exists in Staphylinidce, &c. b The last kind 
I shall notice is when the upper lobe not only consists of 
two joints, but is cylindrical, and assumes the aspect of 
a feeler or palpus c . This is the common character of 
almost all the Predaceous beetles (E?itomophagi Latr,). 
This lobe, which has been regarded as an additional 
feeler, is strictly analogous to the upper lobe in other in- 
sects, and therefore should rather be denominated a pal- 
piform lobe than & palpus. Where there are two lobes, 
the upper one is most commonly the longest; but in 
many species of the tribe last mentioned the lower one 
equals or exceeds it in length d . 

The lobes vary in form, clothing, and appendages. 
The upper palpiform lobe in those beetles just men- 
tioned, in general varies. scarcely at all inform.; but the 
genus Cychrus (which is remarkable for a retrocession 
from the general type of form of the Carabi L. making an 
approach towards that of those Heteromera which, from 
their black body and revolting aspect, Latreille has named 
Melosomes,) affords an exception, the upper joint being 
rather flat, linear-lanceolate, incurved, and covering the 
lower lobe e , which it somewhat resembles. The lower 

a Plate VI. Fig. 6, 12. d"'. e'". Oliv. Ins. no. 45. Meloe. I. i. 
f. I.e. These are what Fabricius calls galeate maxilla?, on which he 
founded his class TJlonata. 

b Plate XXVI. Fig. 11. d'". e'". 

'• Plate VI. Fig. 3. d'". 

d Clairv. Ent. Helvet. t. i. t. xviii./. super, b. 

* Ibid. t. xix. b. This genus may be the analogue of some helero- 



444 EXTERNAL ANATOMY OF INSECTS. 

lobe also in this tribe varies as little as the upper, being 
shaped like the last joint of that lobe in Cychrus just de- 
scribed, except that in Cicindela it is narrowest in the 
middle a . In other tribes the upper valve is sometimes 
linear and rounded at the apex, and the lower truncated, 
as in Staphylinus olens b ; sometimes the upper one is 
truncated or obtuse, and the lower acute, as in Trogosita 
and Parnus c . In Ptinus, another tribe of beetles, be- 
fore noticed as injurious to our museums d , the reverse of 
this takes place, the upper-lobe, which is the smallest 
and shortest, being acute, and the lower truncated e . In 
Blaps both are acute f . In Rhipiphorus and Scolytus the 
lobes are nearly obsolete. The lower lobe is bifid in 
Languria, a North American genus of beetles, so as to 
give the maxilla the appearance of three lobes s ; and in 
Erotylus, a South American one, the upper is triangu- 
lar 11 : it is often oblong, quadrangular, linear, &c. in 
others. — In those that have only one lobe the shape also 
varies. In Gyrinus, the beetle that whirls round and 
round on the surface of every pool, which, though it be- 
longs to the Predaceous tribe, has only one lobe, the lobe 
represents a mandible in shape of the laniary kind, being 

merous one yet undiscovered, as Calosoma is of Adelium (Kirby Linn. 
Trans, xii. t. xxii./. 2.) 

a Clairv. Ent. Helvet. ii. t. xxiv. /. super, b. 

"> Plate XXVI. Fig. 11. 

c Oliv. Ins. no. 19. Trogosita. t. 1./. d. no. 41 bis. Dryops. Li. 
/.I.e. cI See above, Vol. I. p. 238. 

e Oliv. Ins. no. 17. Ptinus. t. i.f. 1. c. 

i Ibid. no. 60. Blaps. t. i.f. 2. c. 

E Ibid. no. 88. Languria. t. i.f. 2. c. 

h Ibid. no. 89. Erotylus. t. ii./. 12. c. 



EXTERNAL ANATOMY OF INSECTS. 445 

trigonal and acute a ; and in the Anoplognathida?, a New 
Holland tribe of chafers, in which it is, as it were, 
broken, the lobe forming an angle with the stalk, it is 
concavo-convex and obtuse, and somewhat figures a 
molary tooth b . In the first tribe into which the bees 
{ApisX») have been divided {Melitta Kirby), the lobe is 
often linear or strap-shaped, and bifid at the apex ; and 
in the second {Apis K.) lanceolate and intire c . In Cero- 
coma it is long: and narrow d . More variations in form 
might be named, but these are sufficient to give you a 
general idea of them in this respect. With regard to 
their clothing, I have not much to observe — in examin- 
ing the Predaceous beetles you will observe, that the in- 
terior margin of the lower incurved lobe is fringed with 
stiff bristles or slender spines, and in many other beetles 
either one or both lobes have a thick coating or brush of 
stiffish hairs e ; but in several cases only the apex of the 
lobe is hairy. In the Orthoptera order, and many of the 
Melolonthidce or chafers, the whole maxilla is without 
hairs, or nearly so. 

The appendages of the maxilla are next to be noticed. 
These are principally their claws, or laniary teeth ; for 
they are seldom armed with incisive or molary teeth. 
The whole tribe of Predaceous beetles, with few excep- 
tions, have the inner lobe of their maxilla armed with a 
terminal claw, which in the Cicindelidce articulates with 
the lobe, and is moveable, but in the rest of the tribe is 

a OJiv. Ins. no. 41. Gyrinus. t. \.f. 1. e. 

b Plate XXVI. Fig. 13. Hor. Entomolog. i. t. m.f. 29, 30. E. 

c Mon. Ap. Angl. i. t. ii. Melitta. **. a./. 2. t. v. Apis. *. b.f. 4. &c. 

d Oliv. Ins. no. 48. Cerocoma. t. i.f. 1. c. 

4 Plate XXVI. Fig. 10—12. 



446 EXTERNAL ANATOMY OF INSECTS. 

fixed a . In PJioberas MacLeay the lower lobe has two 
spines b . In Locusta this lobe has three or four spines 
or laniary teeth, and in JEsk?ia there are six, which, like 
the claw of Cicindela, are moveable c . In others both 
lobes terminate in a single spine or claw : this is the case 
with Paxillus MacLeay d . In Passalus, nearly related 
to the last genus, the upper lobe is armed with a single 
spine, and the lower one with two e . Those maxillce that 
terminate in a single lobe are also often distinguished by 
the spines or teeth with which it is armed ; thus in a 
nondescript chafer belonging to the Dynastidce (Ar- 
c/ion K. MS.) it terminates in two short teeth ; in that re- 
markable Petalocerous genus Hexodon Oliv. in three trun- 
cated incisive ones f ; in Dynastes Hercules in three acute 
spines s . Four similar ones arm the apex of the maxilla 
in that tribe of Rutelidce which have striated elytra ; and 
Jive that are stout and triquetrous those of Melolontha 
Stigma F. Many others have six spines, sometimes ar- 
ranged in a triple series K Besides teeth or spines, in 
some cases the lobes of maxillce terminate in several lono- 
and slender lacinice or lappets fringed with hairs. At 
least those of a Leptura (L. quadrifasciata L.) described 
by De Geer, appear to be thus circumstanced. He con- 
jectures that this beetle uses its maxillce to collect the 
honey from the flowers '. 

a Clairv. Eni. Helvet. ii. Cicindela. t. xxiv./. super, b. for Carabi- 
diB, Dytiscidoe, his other plates. 

b Hor. Entomolog. i. t. ii./. 13. E. c Plate VI. Fig. 6, 12. £'". 

d Hor. Entomolog. t. \.f. 3. E. e Ibid./. 4. E. 

f Oliv. Ins. no. 7. Hexodon. t. i.f. 1. e. 

s Ibid. no. 3. Scarabmus. t. \.f. 1. f. 

k Kirby in Linn. Trans, xiv. 102. t. m. f. 4. d. 

i De Geer v. 417. t. iv.f. 12. 



EXTERNAL ANATOMY OF INSECTS. 447 

As the principal use of the mandibles is cutting and 
masticating, so that of the organs we are considering 
seems to be primarily that of holding the food and pre- 
venting it from falling while the former are employed 
upon it. I say this is their primary use ; for I would by 
no means deny that they assist occasionally in commi- 
nuting or lacerating it. In fact, were there no organs 
appropriated to this use, and if both mandibles and max- 
illa were employed at the same time in comminuting the 
food, it seems to me that it must fall from the mouth. 
In a large proportion of insects the lobes of the maxilla 
are not at all calculated for laceration or comminution ; 
and in those tribes — as the Melolo?ithida> Rutelida, Dy- 
nastidcB — in which they seem most fitted for that pur- 
pose, the mandibles have incisive teeth at their apex, and 
at their base a powerful mola or grinder : circumstances 
which prove, that even in this case the business of mas- 
tication principally devolves upon them. 

6. Palpi Maxillares a . There is one circumstance that 
particularly distinguishes the maxilla from the mandi- 
bles — they are palpigerous, as well as the under-lip. The 
feelers, or palpi, emerge usually from a sinus observable 
on the back of the maxilla where the upper lobe and 
stalk meet. Their articulation does not materially differ 
from that of the labial palpi. Each maxilla has properly 
only one feeler ; but, as was lately observed b , in certain 
tribes the upper lobe is jointed and palpiform, which 
has occasioned it to be considered as a feeler, and these 
tribes have been regarded as having six feelers. The 
most general rule with regard to the length of the palpi 

a Plates VLVII. h". b See above, p. 443. 



448 EXTERNAL ANATOMY OF INSECTS. 

is, that the maxillary shall be longer than the labial ; but 
the reverse often takes place. In many bees the maxil- 
lary consist only of a single joint, and are very short ; 
while the labial consist of four, and are very long a : and 
in some insects (as in Pogonophorus Latr.) the four palpi 
are of equal length b . The antennae are most commonly 
longer than the palpi ; but in several aquatic beetles, as 
Elophorus, Hydrophilus, &c, whose antennae in the wa- 
ter are not in use, the organs we are considering are the 
longest. — As to the number of their articulations, it va- 
ries from one to six ; which number they are not known 
to exceed. In each of the Orders a kind of law seems 
to have been observed as to the number of joints both 
in the maxillary and labial palpi, but which admits of 
several exceptions. Thus in the Coleoptera, the natural 
number may be set at four joints for the maxillary, and 
three for the labial palpi : yet sometimes, as in Stenus, 
Notoxus, &c, the former have only three joints, and the 
latter, as in Stenus and Tillus, only two. In the Ortho- 
ptera the law enjoins^r^ for the maxillary, and three for 
the labial; and to this I have hitherto observed no ex- 
ception. In the Hymenoptera, the rule is six and four, 
but with considerable exceptions, especially as to the 
maxillary palpi, which vary from six joints to a single 
one : thus in the hive-bee and the humble-bee, the la- 
bials, including the two flat joints or elevators, have four 
joints, while the maxillaries are not jointed at all c . In 
Chrysis, in which the latter consist of Jive, the former are 
reduced to three. The Libellulina may almost be re- 

a Mon. Ap. Angl. i. t. ix. 2. c. 2. /3./. 2. d. g. 4. t. xii. neut.f. 6. d. 
t. xiii./. 3. b. *> Clairv. Ent. Helv. ii. t. xxiii./. 1. 

c Plate VII. Fig. 3. b". h". 



EXTERNAL ANATOMY OF INSECTS. 449 

garded as having no maxillary palpi, since they exhibit 
no organ that is distinctly palpiform. It seems to me 
that the upper lobe of their maxilla, which articulates 
with the stalk in the same manner as a feeler, may 
be regarded as an instance in which that lobe and the 
feeler coalesce into one ; and the mucro that proceeds 
from the lobe has the aspect of an emerging feeler, and 
corresponds somewhat with the labial one above no- 
ticed a . In the remainder of the Neuroptera and the 
Trichoptera, the prevailing number is Jive and three. 
In the latter there are exceptions, which will furnish 
good characters for genera. In the Lcpidoptera we find 
two, and sometimes three, the maxillary being very mi- 
nute b . The Diptera Order presents two tribes in this 
respect quite distinct from each other. The most natu- 
ral number of joints in the maxillary palpi of the Tipu- 
lidce, Culicidae, &c. is four or five: the last joint, how- 
ever, in Tipula, Ctenocera, &c. like that of the antennas 
in Tabanus L., appears to consist of a number of very 
minute joints c ; but in the Asilidac and Muscidce, &c, the 
number two seems to be most prevalent^ The labial pal- 
pi in this order are obsolete. — As to shape, the maxillary 
palpi, as well as the labial, are usually filiform ; but in 
the weevil tribes {Curcidio L.) they are most commonly 
very short and conical e ; in the chafers (Scarabccus L.) 
they usually are thickest at the apex f ; in Megachile and 
Euglossa, wild bees, they are setaceous, growing gradu- 



a Plate VI. Fig. 12.b".f". 

b Ibid. Fig. 13. h". Savigny Anhn. sans Vertebr. I. i. 29 — . 
L i. — iii. 6. c De Geer vi. /. xix./. 4. d. 

■' Ibid. t. ix.f. 8. b b. t. xii./. 20. b. t. xiv./. 15. i i. 
e Plate XXVI. Fig. 6. f ' Ibid. Fig. 5, 

VOL. III. 2 G 



450 EXTERNAL ANATOMY OF INSECTS. 

ally more slender from the base to the summit 3 : a tribe 
of small water-beetles (Haliplus), the saw-flies {Ten- 
thredo L.), and several other Hymenoptera, have them 
thickest in the middle b . Their most important part, 
however, and that which varies most in form, is the ter- 
minal joint: — of this I have already related some singular 
instances c , and shall now describe a few more. This 
joint is sometimes acute, at others blunt, at others trun- 
cated: in figure it is ovate, oblong, obtriangular, hatchet- 
shaped, lunate, transverse, conical, mammillate, subulate, 
branched, chelate, laciniate, lamellate, &c. &c. d : terms 
which I shall more fully explain to you hereafter, and 
which I only mention here to show the numerous varia- 

a Kirby Mon. Ap. Angl. i. t. x. Apis. **. c. 2. l.f. 3. a. and **. d. 1. 
f.l.d. ' 

b Clairv. Ent. Helvet. ii. t. xxxi./. super, b. Mon. Ap. Angl. i. t. xiv. 
f.l.k.f.3,5.c. 

c See above, p. 317. 

d Plate XXVI. Fig. 1. As the very remarkable maxillary palpi 
of that extraordinary Coleopterous genus Atractocerus seem not to 
have been so fully described as they deserve, I shall give here a mi- 
nute detail of their composition. They consist of four joints : the 
first is wide and short, and somewhat platter-shaped; the second is 
much smaller and shorter : the third is concavo-convex, or shaped 
like a shallow bowl : towards the breast this joint is elevated, and 
on the elevated edge sits the last joint, which is longer than all the 
rest taken together. In my specimen it points towards the breast ; 
its under side is entire and slightly curved, but in the upper side are 
two rows of lamellae (b), placed alternately nine on each side, with an 
odd one at the end : these lamella? are full of minute papillae, and 
furrowed on the side next the mouth. From between the first pair 
a slender exarticulate hairy branch or appendage emerges («), which 
forms nearly a right angle with the main stem. The labial palpi 
appear to consist of three joints ; the two first very short, and the last 
large, ovate, and acute. This description is not taken from A. necy- 
daloides, but from a Brazilian species more than five times its size, 
which I have named A. Gigas, 



EXTERNAL ANATOMY OF INSECTS. 451 

tions as to figure, of which this joint exhibits examples. 
The palpi in general at their vertex are often rather con- 
cave ; and this concavity is formed by a thin papillose 
membrane, which it is supposed the animal has the 
power of pushing out a little, so as to apply it to sur- 
faces. The "primary use of the palpi of insects will be 
considered when I treat of their senses; but they proba- 
bly answer more purposes than one. For instance, when 
I was once examining, under a lens, the proceedings of 
a species of Mordella, which was busily employed in the 
blossom of some umbelliferous plant, it appeared to me 
to open the anthers with its maxillary palpi, and they 
often held the anther between them : when not so em- 
ployed, they were kept in intense vibration, more than 
even its antennas ; and at the same time, as far as I could 
judge, an Elater made the same use of them. 

7. Lingua a . — This name was applied by Linne to the 
part in insects representing the tongue in vertebrate ani- 
mals ; and as it performs most of the common offices of 
a tongue, and the pharynx is situated with respect to it, 
as we shall presently see, nearly as it is in those ani- 
mals, there seems no more reason for giving it a new 
name, than there is for giving a new name to the head 
or legs of insects, because in some respects they differ 
from those of the higher animals. I shall not therefore 
call it Ligula, with Fabricius and Latreille, nor Labium, 
with Cuvier and others, but adhere to the original term, 
which every one understands. 

The tongue lies between the two lips — the lahrum and 
labium. On its upper side, at the base, it meets the pa- 

■ Plate VI. VII. XXVI. e'. 

2 G 2 



452 EXTERNAL ANATOMY OF INSECTS. 

late or roof of the mouth, below which it is attached, it 
may be pi*esumed, by its roots to the crust of the head, 
on each side the pharynx or swallow ; and on its lower 
side, in many cases, it is attached to the labium, and that 
very closely, so as to appear to be merely a part of it, 
and to form its extremity: but in the Orthoptera and 
Libellulina, it is more free, and in form somewhat re- 
sembling the tongue of the quadrupeds a . — In substance 
the tongue varies. In general it seems something be- 
tween membrane and cartilage ; but in the Predaceous 
beetles, in which it is not covered by the labium, it ap- 
proaches nearer to the substance of the general inte- 
gument, and in Anthia F. it is quite hard and horny: — 
that just mentioned of the Orthoptera and Libellulina 
is more fleshy b . With regard to its station, in many 
cases, as in the instance just named, in the Lamellicorn 
tribe (Scarabceus L.) and others, it is, when unemployed, 
concealed within the mouth ; the lips, mandibles, and 
maxillae all closing over it. The tongue of some Hy- 
menoptera also is retractile within the mouth. " When 
ants are disposed to drink," says M. P. Huber, " there 
comes out from between their lower jaws, which are 
much shorter than the uppei", a minute, conical, fleshy, 
yellowish process, which performs the office of a tongue, 
being pushed out and drawn in alternately: it appears 
to proceed from the lower-lip.— This lip has the power 
of moving itself forwards in conjunction with the lower 
jaws : and when the insect wishes to lap, all this appa- 
ratus moves forward ; so that the tongue, which is very 
short, does not require to lengthen itself much to reach 

a Plate VI. Fig. 6, 12. e', Cuvier Anat. Com far. iii 347. 
b Cuvier Ibid. 



EXTERNAL ANATOMY OF INSECTS. 453 

the liquid V M. Lamarck thinks that the labium of 
insects has a vertical motion (de haul en has ou de has 
en haut) b . This it certainly has in some degree; but it 
has also, as in the above case, a more powerful horizon- 
tal one, which is produced, in Hymcnoptera at least, 
by the opening of the maxillae — as I have already ob- 
served c . 

I have little to say with respect to the structure of the 
tongue: it generally seems to be without articulations; 
but in many bees it articulates with the labium where it 
enters it, so as when unemployed to form a fold with it. 
In the hive-bee it terminates in a kind of knob or button, 
which has been falsely supposed to be perforated for im- 
bibing the honey by suction. The upper part of this 
tongue is cartilaginous, and remarkable for a number 
of transverse rings : below the middle, it consists of a 
membrane, longitudinally folded in inaction, but capa- 
ble of being inflated to a considerable size : this mem- 
branous bag receives the honey which the tongue, as it 
were, laps from the flowers, and conveys it to the pha- 
rynx d . In Stenus this organ is retractile, and consists 
of two joints e . 

The shape of the tongue of insects probably varies as 
much as any other part ; but as it is apt to shrink when 
dried f , and is not easy to come at, we know but little of 
its various configurations : — in the bees it is very long, 
in most other insects very short. Though frequently 
simple and undivided, in many cases it presents a diffe- 
rent conformation. Thus in the saw-flies ( Tenthredo L.) 

• l Huber Fourmis, 4—. b Anim. sans Vertebr.m. 304. 

c See above, p. 440. '• Reaum. v. 309 — . 

- Plate XXVI. Fig. 23. i Clairv. Ent. Helvet. ii. Pref. xxii. 



451 EXTERNAL ANATOMY OF INSECTS. 

it terminates in three equal lobes a ; in Stomis and Geo- 
trupes in three unequal ones, the intermediate being very 
short b ; in Carabus, in three short teeth c ; in Pogonopho- 
rus it represents a trident d ; in the wasp it is bifid, each 
lobe being tipped with a callosity e ; in Melolontha Stigma 
it is bipartite t '; in Elaphrns, the analogue of the tiger- 
beetles, it terminates in a single tooth or point; in the 
aquatic beetles, Dytiscus L., it is quadrangular and with- 
out teeth s ; in some Ichneumonidce it is concavo-convex, 
and forms a demitube; and in others it is nearly cylin- 
drical h . 

In many insects it has no kairs, but in the Predaceous 
beetles it generally terminates in a couple of bristles '. 
In the hive- humble- and other bees, it is extremely 
hairy k ; a circumstance which probably enables it more 
effectually to despoil the flowers of their nectar. In Geo- 
trupes stercorarius, the common dungchafer, and Melo- 
lontha Stigma lately mentioned, the lobes of the tongue 
are fringed with incurved hairs *; and in JEshna it is 
hairy on the upper side, each hair or bristle crowning a 
minute tubercle. In many cases the tongue is attended, 
and sometimes sheathed at the base, by two usually mem- 
branous appendages : — these the learned Illiger has deno- 



. a Kirby Moiu Ap. Angl. i. t. xiv. (1) 2. b. 

h Plate XXVI. Fig. 24. e'. c Clairv. ubi supr. t. xx. c. 

d Plate XXVI. Fig. 28. e. 

e Kirby ubi supr. fig. (8) 1. c c. The lateral pieces in the tongue 
in -Vespa {Ibid, c c.) have been regarded as lobes of it, but they are 
rather Paraglossce. 

f Plate XXVI. Fig. 29. e'. e Clairv. ubi supr. t. xxx. c. 

» Kirby ubi supr. no. 2./. 1, 3. '' Plate XXVI. Fig. 24. b. 

k Kirby ubi supr. 1. x. Apis. e. 2. §./. 5. t. xii. neut.f. 2, 3. t. xiii. 
/. 1. h. l Plate XXVI. Fig. 26, 29. 



EXTERNAL ANATOMY OF INSECTS. 455 

minated paraglossce ; and I shall adopt his term. You 
will find them frequently attached to the tongue of the 
Predaceous beetles a , and to that of many Hymenoptera. 
In the hive-bee and humble-bee they are short, and take 
their origin within the labial feelers b : in Euglossa, an- 
other bee, they are long, involute at the tips, and, what 
is not usual with them, very hairy c : in the wasp, like 
the lobes of the tongue, they are tipped with a callosity. 
Under this head I may observe to you, that the in- 
sects whose oral organs we are considering besides a 
tongue appear likewise to be furnished with & palate [Pa- 
latum). This, though a part of the roof of the mouth, 
is not precisely in the situation of the palate of vertebrate 
animals, since it seems rather the internal lining of the 
labrum. If you take the common dragon-fly (JEsh?ia 
viatica), you will find that the under side of this part 
and of the rhinarium is lined with a quadrangular fleshy 
cushion, beset, like the upper surface of the tongue, with 
minute black tubercles, crowned with a bristle. This 
cushion is divided transversely into two parts by a de- 
pression ; the anterior or outer piece being attached to 
the labrum, and the other piece to the rhinarium. The 
former has a central longitudinal cavity, black at the 
bottom, on the sides of which the tubercles are flat and 
without a bristle. From its base on each side a spini- 
form process emerges, forming a right angle with it. 
These processes seem the antagonists of those mentioned 
above d , that emerge from the labium. The posterior or 

a Plate XXVI. Fig. 28. i". 

11 Kirby Mon. Ap. Angl. i. t. xii. neat.f. \.hh. t. xiii./. l.ff. 

c Ibid. t.x.**. d, l.f.2.bb. 

ll See above, p. 425. 



1-56 EXTERNAL ANATOMY OF INSECTS. 

inner piece has on each side a roundish space, attached 
to the under surface of the t\vo sides of the rhinarium, 
beset also with bristle-bearing tubercles. You will find 
something similar lining the labrum and nasus of some 
Coleoptera, — say Geotrupes, Necrophorus, and Dytiscus. 
The first piece I regard as the analogue of the palate, and 
the second as connected with the sense of smelling. In 
Necrophorus the circular pieces are covered with a finely 
striated membrane, and in Dytiscus each has a little 
nipple. 

8. Pharynx a . — On the upper side of the tongue, usu- 
ally at its base or root, is the pharynx, or aperture by 
which the food passes from the mouth to the oesophagus. 
This orifice, which is situated with respect to the tongue 
of the Orthoptera and Libellulina nearly as in those in- 
sects (at least as far as I have been able to examine them), 
whose tongue is called a ligula or labium, — of course ex- 
ists in all the mandibulate Orders whose mouth we are 
now considering. In the Hymenoptera it is covered by a 
valve, the Epipharynx of Savigny; and it appeared to me 
to be so likewise in one of the Harpalidce that I examined. 
The formation seems different in Geotrupes, as far as I 
can set an idea of it: but it is so difficult to examine the 
interior of the mouth without laceration of some of the 
parts, that I can only tell you what the appearances were 
in one instance, upon removing the labrum from the man- 
dibles; and in another, separating the whole apparatus 
of the labium, including the maxilla:, from the mandibles 
and labrum. In the former case, the mandibles coincided 

il Plate VII. Fig. 14. f, 



EXTERNAL ANATOMY OF INSECTSr 457 

at the base, the two molary plates (molce), which in this 
genus are narrow, transverse and not furrowed, are so 
applied as evidently to have an action upon each other, 
as the mandible opens and shuts, proper for trituration. 
Within these is the base of the tongue, under the form 
of a ventricose sack. The upper part of this last organ, 
which forms the internal covering of the labium, appears 
to consist of three (in the recent insect jleshy) lobes, the 
middle one being bent downwards internally, so as to 
form a kind of sloping cover to an orifice in the part 
I call the base. After two or three days, the tongue 
shrinks and dries to a hard substance; — between the man- 
dibles and the base of the tongue I could not discover 
the pharynx. The above apparent opening covered by the 
tongue was the only one I could perceive. In the latter 
case, the form and structure of the base of the tongue is 
more visible: it is an oblong ventricose tubular sack, 
projecting above anteriorly into an acute angle formed 
by a fine white membrane, most beautifully and deli- 
cately striated with oblique striae, to be seen only under 
a powerful lens : on the anterior side of this sack are two 
parallel cartilaginous ridges close to each other, fringed 
with short hairs, which take their origin from the angle. 
I could not be certain whether the orifice covered by 
the intermediate lobe was only apparent, or real ; but I 
did not succeed in my endeavour to find any other pha- 
rynx, though from the molary structure of the base of 
the mandibles one may conjecture that there must be one 
situated at the base of this sack to receive the food they 
render after trituration. The excrement of this animal 
is not fluid. In the Libellulina the pharynx seems 
closed by two valves meeting. This part in Hymeno- 



458 EXTERNAL ANATOMY OE INSECTS. 

ptera, and probably in other Orders, has the aspect of 
beino- cartilaginous and fitted to sustain the action of the 
substances that have to pass through it a . 

The Epipharynx is a valve, called by M. Latreille 
sublabrum (sous labre b ), attached by its base to the upper 
margin of the pharynx, or that next the labrum. In 
the bees it is said by Reaumur to be of a fleshy substance, 
and capable of changing its figure. He seems to think 
it the real tongue of the bee c ; but as it does not appear 
to have any of the uses of a tongue, and merely closes 
the orifice of the mouth, it surely does not merit that 
name. M. Savigny calls it a membranous appendage 
which exactly closes the pharynx^. De Geer has exa- 
mined the epipharynx of the wasp, which he describes as 
of a scaly substance, and regards merely as the cover of 
the part just named c . 

With regard to the Hypopharynx, which Latreille con- 
siders as a support and appendage of the epipharynx, I 
have little to add to the definition I have given of it above. 
In the Libellulina the base of the tongue terminates 
towards the pharynx in a fleshy cushion, armed at each 
angle next to that part with a short hard horn or tooth 
of a black colour. This cushion, I suppose, may be ana- 
logous to the hypopharynx of M. Savigny f . On the oppo- 
site side the pharynx is closed by another fleshy cushion 
(epipharynx?), which appears to line the nose, behind 
those two mammillae before described s, which form the 
internal covering of the rhinarium. 

Reaum. v. 31 /• b Organisation exterieur des Ins. 184. 

c Ubi supra. <i Anim. sa?is Vertebr. I. i. 12. 

e DeGeer ii.778— . /. xxvi.f. 11. m. Plate VII. Fig. 2. k". 
i Ubi supra. % See above, p. 455. 



EXTERNAL ANATOMY OF INSECTS. 459 

Before I call your attention to what I would' denomi- 
nate an imperfect month, in which some one or more of 
the seven organs above enumerated exist under another 
form, or only as rudiments, — I must say something upon 
the mouth of the Myriapods and Arachnida, in which 
there seem to be redundant organs of manducation. — 
M. Latreille, in the Essay lately quoted, in which, 
though some of his notions seem fanciful, he has shown 
a vast depth and range of thought and research, has as- 
serted, — from the admirable and curious observations of 
M. Savigny, and those which since their publication he 
has made himself, — that the masticating organs of an- 
nulose animals (called by him condylopes) are a kind of 
legs a . And M. Savigny, whose indefatigable labours 
and unparalleled acuteness have opened the door to a 
new and vast field in what may be denominated analo- 
gical anatomy, — has observed, that with certain Apiro- 
pods b the organs that serve for manducation do not dif- 
fer essentially from those which, with the other Apiro- 
pods and the Hexapods, serve for locomotion c : and the 
unguiform mandibles of the larvae of certain Diptera, 
you have before been told, are used not only in mandu- 
cation, but also as legs d . These remarks will satisfac- 
torily prove to you, that organs which at first sight pos- 
sess no visible affinity or analogy — as for instance, jaws 
and legs — may, if traced through a long series of beings, 
exhibit a very great one ; — and will lessen your surprise 

a Organisation &c. 182. 

b Under this name M. Savigny includes the Myriapoda, Arach- 
nida, and Crustacea. Anim. sans Vertebr. I. i. 40. 
c Ibid. 43. 
d Vol. II. p. 275 — . Also see abovc^ p. 121 — . 



4>60 EXTERNAL ANATOMY OF INSECTS. 

when you find, that in certain tribes such commutations 
of organs and their use take place. 

The following is the structure, as to its organs, of the 
mouth of the myriapods, as exhibited by the centipedes 
(Scolopendrides). The part which appears to perform the 
office of the upper lip (but which M. Savigny regards 
as the nose, calling it the chaperon,) is a transverse piece 
with a deep anterior sinus, in the centre of which is a 
minute tooth a . This piece is separated from the fore- 
part of the head by a suture; but it probably is not move- 
able: however, it covers the mouth, and may be regarded 
rather as analogous to the labrum. Below this are two 
mandibles, armed at their end with five sharp triangular 
teeth 5 , under which are the maxillce, terminating in a 
moveable concavo-convex lobe, resembling the valve of 
a bivalve shell c ; and between them is the labium, of a 
rhomboidal shape, divisible into two lobes, attached la- 
terally to the maxillae : these lobes M. Savigny terms the 
second maxillae, forming with the others, according to 
him, the labium d . Affixed to the base of this labium, or 
covering it on the outside, are a pair of pediform palpi, 
which he considers as the first auxiliary labium, and re- 
presentative of the first pair of legs of hexapods and Iuli e . 
I imagine them to be also the analogues, in some degree, 
of the labial palpi of a perfect mouth. The last of the 
organs in question is a large rhomboidal plate affixed to 
the first apparent segment of the trunk, crowned at its 
vertex with two truncated denticulated teeth, and from 

3 Anim. sans Vertebr. I. i. t. W.f. 2. a. a'. 

b Plate VII. Fig. 13. c'. « Ibid. d'. 

d Anim. sans Vertebr. I. i. 10G. Plate VII. Fig. 13. b'. 

e Ubi supr. 45 — . 



EXTERNAL ANATOMY OF INSECTS. 461 

the upper sides of which emerge a pair of moveable or- 
gans terminating in a powerful incurved claw, and which 
entirely covers all the other parts of the mouth a . This, 
M. Savigny deems as a second auxiliary labium, and the la- 
teral organs of prehension,— which may be regarded each 
as a kind of maxillary hand, and as the only representa- 
tives" in this tribe of the maxillary palpi, though widely 
different, — he looks upon as really analogous to the second 
pair of legs in lulus and the hexapods b . These two pairs 
of pedipalpes (to use an expressive French term) show 
their relation to legs by their general structure, and their 
analogy with palpi by their use as oral organs, though 
belonging to the trunk : so that here we see the legs and 
their appendages assume a material function in mandu- 
calion, forming a singular contrast to what we had ob- 
served before with regard to mandibles becoming instru- 
ments of locomotion. The mouth of the Iulidce, with lit- 
tle variation, is upon the same plan c with those here de- 
scribed. 

The next type of form with regard to the oral organs 
is that of the Arachnida. In these, as you know, the 
head is confounded with the trunk ; so that they are a 
kind of Blemmyes in the insect world. Their organs of 
manducation, amongst which there is no labrum or upper 
lip, are, in the first place, a pair of mandibles planted 
close and parallel to each other in the anterior part of 
the head, which they terminate. In the spiders they con- 
sist of two tubular joints, of which the first is much the 
largest, more or less conical or cylindrical, and armed 



a Plate VII. Fig. 11./', a . b Ubi supra, 45. 

«= Ibid. 44—. 



4-62 EXTERNAL ANATOMY OF INSECTS. 

underneath with a double row of stout teetli ; and the 
terminal one is more solid and harder, in the form of a 
very sharp crooked claw, which in inaction is folded on 
the first joint between the teeth. Under its extremity on 
the outside is a minute orifice, destined to transmit a ve- 
nomous fluid, which is conducted there by an internal 
canal from the base of the first joint, where is the poison- 
bag a . In the scorpion and harvest-man (Phalangium) 
the mandible consists of two joints terminated by a chela 
or double claw, the exterior one being moveable 5 . — ■ 
M. Latreille, as has been before observed, regards these 
not as representatives of the mandibles of hexapods, but 
as replacing the interior pair of antennas, in the situation 
of which they are precisely placed, of the Crustacea c : 
and M. Savigny is of opinion that the Arachnida may in 
some sort be defined as Crustacea without a head, and 
with twelve legs, of which the two first pair are converted 
into mandibles and maxilla?'*-. From the situation of the 
organs in question, the first of these opinions seems pre- 
ferable ; but the conversion of the legs in other cases, at 
least the coxae, into organs of manducation, gives some 
weight to the last. With regard to their use, it is said 
to be to retain the insect which the animal has seized, 
and to facilitate the compression which the maxillae exer- 
cise upon it for the extraction of the nutritive matter e . 
If this be correct, in this respect the mandibles may be 
said to represent the maxillae of the mandibulate hexa- 
pods ; and, vice versa, the sciatic maxillae, as they have 

a N. Diet. d'Hist. Nat. ii. 275—. Plate VII. Fig. 10. c'. 
b De Geer t. xl./. 4. t. x.f. 7, 8. c See above, p. 18, 30 

d Savigny Anim. sans Vertebr. I. i. 62. 
e N. Diet. d'Hist. Nat. ii. 277. 



EXTERNAL ANATOMY OF INSECTS. 463 

been denominated % of the Arachnida, their mandibles. 
The palpi are pediform, and the first joint of the coxa, 
or hip, acts the part of a maxilla : — this is composed of 
a single piece or plate, more or less oval or triangular, 
sometimes straight and sometimes inclined to the labium, 
with the interior extremity very hairy. The labium con- 
sists also of a single piece, and is only an appendage of 
the anterior extremity of the breast. The interior of 
the mouth, or palate, presents a fleshy, hairy, linguiform 
piece, which is usually applied to the internal face of the 
labium. An opening is supposed to exist in its sides, for 
the transmission of the alimentary juices b . If you ex- 
amine the under side of the body of a scorpion, you will 
find that not only the palpi, but the two anterior pair of 
legs, by means of their coxa, are concerned in mandu- 
cation : so that these insects have in fact three pairs of 
maxillae — a circumstance that M. Savigny has observed 
to take place also in the harvest-men (Phalangium L.) c . 
The palpi of the scorpion, which may be called its hands, 
like the anterior legs of the lobster and crab, terminate 
in a tremendous chela or forceps, consisting of a large 
triangular joint, armed at the end with a double claw 
internally toothed ; the exterior one of which, contrary 
to what takes place in the animals just named, is move- 
able, and not the interior d . 

Havino- given you this full account of the trophi of 
those animals that have all the organs of manducation 
developed, I must next advert to those in which one part 

* N. Diet. d'Hist. Kat. ii. 276. b Ibid. 

- Ubi supr. 58. d Plate XV. Fig. 7- 



46 1< EXTERNAL ANATOMY OF INSECTS. 

receives an increment at the expense of others, and the 
whole oral machine is fitted for suction ; or where some 
parts appear to be deficient, so that this may be called 
an imperfect mouth. At first sight one would regard the 
trophi of a bee as of this description ; but this is not the 
case, since it has all the ordinary organs, though the 
tongue is unusually long, and looks as if it was made for 
suction ; which, however, as you have been informed, is 
not the case. 

There are Jive kinds of imperfect mouth to be met 
with in insects that take their food by suction, each of 
which I shall distinguish by a separate denomination. 
The first is that of the Hemiptera Order : — this I term 
the Promuscis; the second is that of the Diptera, which 
with Linne I call Proboscis ; the third, peculiar to the 
Lepidoptera, is with me an Antlici; the fourth, which I 
name Rostrulum, is confined to the Aphaniptera order, 
or genus Pulex L. ; and the last is Rostellum, which I 
employ to denote the suctory organs of the louse tribe 
(Pediculidte). 

1. Promuscis a . — The organ we are first to consider 
has usually been denominated Rostrum : but since that 
term is likewise in general use for the snout of insects of 
the weevil tribes [Curculio L.), I think you will concur 
with me in adopting the one here proposed, for the very 
different oral instruments of the Hemiptera. Illiger has 
employed promuscis to denote those ofbees b : but since, as 
I have just observed, they consist of all the ordinary or- 
gans, they seem to require no separate denomination : 

a Plate VI. Fig. 7-9. a', b', c', d'. b Magr/z. 1806. 



EXTERNAL ANATOMY OV INSECTS. 465 

the term, therefore, may be applied to represent a diffe- 
rent set of tropin, without any risk of producing confu- 
sion. This part consists of Jive pieces : viz. a minute, 
long, conical piece, commonly very slender, which covers 
the base of the promuscis, and represents the labrum a ; a 
jointed sheath (vagina), consisting of either three or four 
joints, the analogue of the labium, and four slender rigid 
lancets (scalpella), the two exterior ones, according to 
M. Savigny, representing the mandibles, and the inter- 
mediate pair the maxilla; b . By the union of these four 
pieces a suctorious tube is formed, which the animal in- 
serts into the substance, whether animal or vegetable, 
the juices of which form its nutriment. These pieces are 
dilated at their base, and serrated at their apex ; and the 
two central ones, though at their origin they are asun- 
der, form one tube, which has often been mistaken for a 
single piece. A pharynx and tongue have been disco- 
vered by M. Savigny in this apparatus ; who thinks that 
in Nepa there are also rudiments, but very indistinct, of 
labial palpi : so that the maxillary j^olpi seem to be the 
only part absolutely wanting c « 

The Promuscis when at rest is usually laid between 
the legs; but when employed, in most cases its direction 
is outward. In the genus Chermes L. [Psylla Latr.) the 
origin of the promuscis has been supposed to be in the 
breast; but if closely examined, this anomaly in nature 
will be found not to exist. If you take one of these in- 
sects, the first thing that strikes you upon inspecting the 
head, is a pair of remarkable conical processes into which 

a Plate VI. Fig. 7. a'. 

b Ibid. Labium b'. Mandibular c'. Maxilla? d'. 

c Savigny Anim. sans Vertebr. I. i. 37- 

VOL. III. 2 H 



4-G6 EXTERNAL ANATOMY OF INSECTS. 

the front appears to be divided. Look below these, and 
you will there discover the upper-lip : and from this you 
may follow the promuscis till it gets beyond the forelegs, 
when it takes a direction perpendicular to the body a ; a 
circumstance which has given rise to the above false no- 
tion. Though in Coccus, Chermes, &c. this instrument is 
short, in some Aphides it is longer in proportion than in 
any other insect. In A. Querents it is three times the 
length of the body; so that when folded, it stretches out 
beyond it, and looks like a long tail b ; and in A. Abietis 
it even exceeds that length c . 

ii. Proboscis d . — Linne long since, and after him Fa- 
bricius, has employed this term to designate the oral in- 
struments, or rather their sheath, in the Muscidce and 
some others, calling the same organ, when without fleshy 
lips, rostrum and haustellum: but as the parts of the 
mouth in all true Dijptera (for Hippobosca and its affinities 
can scarcely be deemed as co-ordinate with the rest), are 
analogous to each other ; although in some they are stiff 
and rigid, in others flexile and soft, and in GUstrus (ex- 
cept the palpi) mere rudiments, — the same appellation 
ought to designate them all. I am happy to find that 
M. Latreille agrees with me in this opinion ; and to his 
sensible observations on this head, if you wish for further 
information, I refer you e . The mouth of Dipterous in- 
sects appears to vary in the number of pieces that it pre- 



a De Geer iii. 137—. t. ix.f. 4. 
b Reaum. iii. 335. t. xxviii./. 8 — 14. 
c De Geer iii. 117. t.vm.f. 22. b. 
11 Plate VII. Fig. 5, 6. a', b', c', d\ 
e N. Diet. d'Hitt. Nat. iv. 253. 



EXTERNAL ANATOMY OF INSECTS. 46'7 

sents ; but in all, the theca or sheath is present, which re- 
presents the labium (including the mentum) of the man- 
dibulate Orders a . It consists of three joints, the last of 
which is formed by the liplets {Lobelia). Those in the 
Muscidce are large, turgid, vesiculose, and capable of 
dilatation ; in the Bombylidce and other tribes they are 
small, slender, long and leathery, and sometimes re- 
curved. The second joint or stalk, which may be said 
to represent the mentum, the liplets being properly in a 
restricted sense the analogue of the labium , its sides being 
turned up, forms a longitudinal cavity, which contains 
the haustellum. The upper piece of this, the valvula, is 
long, rigid, and very sharp, representing the labrum b . 
Beneath this cover, in the above cavity, are the lancets ; 
which, as far as they are at present known, vary in num- 
ber and form: sometimes there are Jive of them, some- 
times four, sometimes two, and sometimes, it should seem, 
only one c . In the gnat {Culex) they are finer than a 
hair, very sharp, and barbed occasionally on one side d ; 
in the horse-fly {Tabanus L.) they are flat and sharp like 
the blade of a knife or lancet e . In this tribe the upper 
pair, or the knives [Ctdtelli), represent the mandibles; 
the lower pair, or the lancets (Scalpella), usually palpi- 
gerous, the maxillce ,• and the central one the tongue. In 
the horse-fly Reaumur has figured only four, exclusive 
of the lalrrum and labium ; but in a specimen I have pre- 

3 Plate VII. Fig. 5, 6. a'. b Ibid. 

c Reaum. iv. t. XVI. Fig. 13. z. 

d Authors are not agreed as to the precise number of lancets con- 
tained in a gnat's proboscis. Swammerdam affirms there are six, in- 
cluding the labrum. i. 156. b. t. xxxii./. 3. Reaumur could find only 
five. iv. 597 — . t. xlii./. 10. And Leeuwenhoeck only four. 

e Plate VII. Fig. 5. 

2 H 2 



4GS EXTERNAL ANATOMY OF INSECTS. 

served there appear to he Jive, one of which, as slender 
as a hair, I regard as the analogue of the tongue a . — 
When the lancets are reduced to two, they probably re- 
present the maxilla?, the mandibles being absorbed in 
the labrum ,■ and where there is only one, the maxillee 
also are absorbed by the labium, which then bears the 
palpi, the lancet representing the tongue b . The lancets 
are so constructed in many cases, as to be able by their 
union to form a tube proper for suction, or rather for 
forcing the fluid by the pressure of the lower parts to the 
pharynx c . Labial palpi appear not usually present in 
the proboscis ; but M. Savigny thinks he has discovered 
vestiges of them in Tabanus d . In this genus the maxil- 
lary ones are large, and consist of two joints e . The pro- 
boscis is often so folded, as to form two elbows; the base 
forming an angle with the stalk, and the latter with the 
lips, so as in shape to represent the letter Z, only that the 
upper angle points to the breast, and the lower one to 
the mouth : this is the case with the flesh-fly and many 
others. In other flies, as Conops and Stomoxys, whose 
punctures on our legs so torment us f , there is only a 
single fold, with its angle to the breast. The proboscis is 
received in a large oblong cavity of the underside of the 
anterior part of the head. 



a Plate VII. Fjg. 5. This figure is copied from Reaumur, and 
was engraved before this discovery was made. 

b M. Savigny is of opinion that the central lancet or lancets re- 
present the Epipharynx and Hypopharynx ; for which he does not 
state his reasons : but as these are properly covers of the pharynx, 
the idea seems incorrect. Ubi supr. 15. 

c N. Diet. a" Hist. Nat. ix. 489. and iv. 253—. 

d Ubi supr. 36. « Ibid. t. iv./. 1. o. o. 

f Vol. I. p. 48, 110—. 



ETERNAL ANATOMY OF INSECTS. 469 

It may here be observed, that in the promuscis the 
elongation of the organs seems to be made chiefly at the 
expense of all the palpi, but in the proboscis at that of 
the labial only; and in some cases at that also of the 
mandibles or maxilla?, — the former merging in the la- 
brum and the latter in the labium. 



iii. Antlia a . — The third kind of imperfect mouth is that 
of the Lepidoptera, which I have called Antlia. Fabri- 
cius denominates it lingua; but as this organ has no ana- 
logy with the real tongue of insects, this is confessedly 
improper, and it appeared necessary therefore to exchange 
it for another denomination : I have endeavoured to ap- 
ply a term to it that indicates its use — to pump up, name- 
ly, the nectar of the flowers into the mouth of the insect. 
On a former occasion I described to you the structure of 
this instrument 5 ; but further discoveries with regard to 
it having since been made by MM. Savigny and La- 
treille, I shall here give you the result of their observa- 
tions. The former of these able physiologists has de- 
tected in the mouth of the Lepidoptera rudiments of al- 
most all the parts of a perfect mouth. Of the correct- 
ness of this assertion you may satisfy yourself, if you con- 
sult his admirable elucidatory plates, and compare them 
with the insects. Just above the origin of the spiral 
tongue or pump, the head is a little prominent and 
rounded ; and immediately below the middle of this pro- 
minence there is a very minute, membranous, triangular 
or semicircular piece ; which from its position, as cover- 
ing the base of the antlia, may be regarded as the rudi- 

* Plate VI. Fig. 13. a', h' } c, d'. b Vol. I. p. 394—. 



4 TO EXTERNAL ANATOMY OF INSECTS. 

ment of the upper-lip (labrum) a . On each side of the 
outer base of the antlia is another small immoveable 
piece, resembling a flattened tubercle, the end of which 
is internally hairy or scaly: these pieces appear to repre- 
sent the mandibles, b . Near the base of each half of the 
antlia, just below a sinus, may be distinctly seen the mi- 
nute, usually Particulate rudiment of a maxillary pal- 
pus' 1 ; demonstrating to a certainty that these spiral or- 
gans, at least their lateral tubes or Solenaria, are real 
maxillae d . The rudiment of the under-lip {Labium) is 
the almost horny triangular piece united by membrane 
to the two stalks of the maxillae, and supporting at its 
base the recurved labial palpi ; which are so well known 
that I need not enlarge upon them e . Amongst these 
parts there seems at first sight no representative of the 
tongue ; but M. Latreille has advanced some very inge- 
nious, and I think satisfactory arguments f , which go to 
prove that this part, at least the tongue of Hymenop>tera 9 
has its analogue in the intermediate tube or Fistula 
formed by the union of the two maxillae, and which con- 
veys the fluid aliment of this Order to the pharynx. As 
in Dipt era the maxillce sometimes merge in the labium, 
so here the tongue (as it were divided longitudinally) 
merges in the maxillce. He further observes, that in a 
transverse section of the maxilla of the death's-head 
hawk-moth {Sphinx Atropos), the lateral tube appeared 



a Plate VI. Fig. 13. a'. Savigny Anim. sans Vertebr. I. i. 3- 
i. i.— iii. a. b Ibid. i. Plate VI. Fig. 13. c'. 

c Ibid. Fig. 13. h". Savigny ubi supr. o. 
d Plate VI. Fig. 13. a". Savigny ubi supr. t. 1 — 3. o. 
c Ibid. o. Plate VI. Fig. 13. b'. 
* A 7 ". Diet. cUHist. Nat. xvii. 467„ 



EXTERNAL ANATOMY OF INSECTS. 471 

to be divided into two by a membranous partition, and 
to contain in the upper cavity a small cylindrical tube, 
which seemed to be a trachea a . To animals that are 
without lungs, and breathe by trachece, suction must be 
performed in a very different way from what it is by 
those that breathe by the mouth : and as in the very ex- 
tended organs in question the fluid has a long space to 
pass before it reaches the pharynx, in some way or other 
these lateral tubes may have the power of producing a 
vacuum in the middle tube, and so facilitate its passage 
thither.- We see, in the antlia, that the maxillae receive 
their vast elongation at the expense of all the other or- 
gans, except the labial palpi. 

iv. Mostrulum h . — An animal very annoying to us af- 
fords the type of the next kind of imperfect mouth — I 
mean the Jlea. Its oral apparatus, which I would name 
rostrulum, appears to consist of seven pieces. First are a 
pair of triangular organs, the lamina, which together 
somewhat resemble the beak of a bird, and are affixed, 
one on each side of the mouth, under the antennae: these 
represent the mandibles of a perfect mouth c . Next, a 
pair of long sharp lancets (Scalpella), which emerge from 
the head below the laminae: these are analogous to max- 
illce^'. a pair of palpi, consisting of four joints, are at- 
tached to these near their base e , which of course are 
maxillary palpu And lastly, in the midst of all is a 
slender setiform organ (ligula), which is the counterpart 
of the tongue f . Rosel, and after him Latreille, seem to 

a N. Diet. d'Hist Nat. iv. 253. 

b Plate VII. Fig. 8. c, d', e , h". c Ibid. c'. 

d Ibid. d'. E Ibid. h". ' Ibid. e. 



472 EXTERNAL ANATOMY OF INSECTS. 

have overlooked this last piece, since they reckon only 
six pieces in the flea's mouth a : but the hand and eye of 
our friend Curtis have detected a seventh, as you see in 
his figure. From this account it appears, that the elon- 
gation of the organs of the Aphaniptera Order is at the 
expense of the labium and its palpi. 

v. Rostellum. — So little is known of the composition 
of the next kind of imperfect mouth, that I need not en- 
large upon it. It is peculiar to the louse tribe [Pedicu- 
lidce\ and it consists of the tubulet ( Tubulus), and si- 
phuncle (Siphuncidus). The former is slenderer in the 
middle than at the base and apex, the latter being tur- 
gid, rather spherical, and armed with claws which pro- 
bably lay hold of the skin while the animal is engaged in 
suction. When not used, the whole machine is with- 
drawn within the head ; the siphuncle, which is the suc- 
torious part, being first retracted within the tubulet, in 
the same way as a snail retracts its tentacula b . This ap- 
paratus seems formed at the expense of all the other 
organs. 

There are some other kinds of imperfect mouth, 
which, though they seem not to merit each a distinct 
denomination, should not be passed altogether without 
notice. The first I shall mention is that of the family of 
Pupipara Latr. (Hippobosca L.). It consists of a pair 
of hairy coriaceous valves, which include a very slender 
rigid tube or siphuncle, the instrument of suction, which 
Latreille describes as formed by the union of two seti- 



3 Rosel. ii. t. iii./. 15. Latreille Gen. Crust, et Ins. iv. 365, 
b Swammenlam Bibl. Nat. t. ii. f. 4. 



EXTERNAL ANATOMY OF INSECTS. 473 

form pieces a . In Melophagus, the sheep-louse, the union 
of the valves of the sheath is so short, that they appear 
like a tube ; but if cut off they will separate, and show 
the siphuncle, as fine as a hair, between them. This or- 
gan is of a type so dissimilar, as was before observed, to 
that of the Diptera in general, and approaches so near to 
that of the dog- tick [Ixodes), that they may be deemed ra- 
ther apterous insects with two wings, than to belong to that 
Order ; and the circumstance that some of the family are 
apterous confirms this idea. In fact they are a transition 
family that connects the two Orders, but are nearest to 
the Aptera. In Nycteribia the oral organs differ from 
those of the other Pupipara in having palpi. This also 
is the case with those of the genus Ixodes, the palpi of 
which are placed upon the same base with the instru- 
ment of suction, than which they are longer : they ap- 
pear to consist of two joints, the last very long and flat. 
The instrument of suction itself is formed by three hard 
rigid laminae ; two shorter parallel ones above, that co- 
ver the third, which is longer and broader, and armed 
on each side with several teeth like a saw, having their 
points towards the base b . Many of the other Acari L. 
have mandibles, and several have not : but their oral or- 
gans have not yet been sufficiently examined ; and from 
the extreme minuteness of most jf them, this is no easy 
task; nor to ascertain in what points they differ or 
agree. 

If you consider the general plan of the organs of man- 
ducation in the vertebrate animals, how few are the va- 

a N. Diet. d'Hist. Nat. xxviii. 266. 

b Ibid, xvi- 432. De Geer vii. t.vi.f. 4. Not quite accurate. 



474- EXTERNAL ANATOMY OF INSECTS. 

nations that it admits ! An upper and a lower jaw 
planted with teeth, or a beak consisting of an upper or 
a lower mandible with a central tongue, form its princi- 
pal features. But in the little world of insects, how won- 
derful and infinite is the diversity which, as you see, in 
this respect they exhibit ! Consider the number of the 
organs, the varying forms of each in the different tribes, 
adjusted for nice variations in their uses : — how gradual, 
too, the transition from one to another ! how one set 
of instruments is adapted to prepare the food for deglu- 
tition by mastication ; another merely to lacerate it, so 
that its juices can be expressed; a third to lap a fluid 
aliment ; a fourth to imbibe it by suction — and you will 
see and acknowledge in all the hand of an almighty and 
all-bountiful Creator, and glorify his wisdom, power, 
and goodness, so conspicuously manifested in the struc- 
ture of the meanest of his creatures. You will see also, 
that all things are created after a pre-conceived plan ; in 
which there is a regular and measured transition from 
one form to another, not only with respect to beings them- 
selves, but also to their organs — no new organ being pro- 
duced without a gradual approach to it; so that scarcely 
any change takes place that is violent and unexpected, 
and for which the way is not prepared by intermediate 
gradations. And when you further consider, that every 
being, with its every organ, is exactly fitted for its func- 
tions ; and that every being has an office assigned, upon 
the due execution of which the welfare, in certain re- 
spects, of this whole system depends, you will clearly 
perceive that this whole plan, intire in all its parts, must 
have been coeval with the Creation ; and that all the 
species,- — subject to those variations only that climate 



EXTERNAL ANATOMY OF INSECTS. 475 

and different food produce, — have remained essentially 
the same, or they would not have answered the end for 
which they were made, from that time to this. 

Having given you this particular account of the trophi 
or organs of the mouth of insects, I must now make some 
observations upon the other parts of the head. I have 
divided it, as you see in the Table, xntoface and subface; 
the former including its upper and the latter its lower 
surface. Strictly speaking, some parts of the face, as the 
temples and cheeks, are common to both surfaces ; but 
I do not therefore reckon them as belonging to the sub- 
face, which, exclusive of the mouth and its organs, con- 
sists only of the throat, and where there is a neck, the 
gida. 

i. Nasus a . — I shall consider the parts of the face in the 
order in which they stand in the Table, beginning with 
the nasus or nose. Fabricius has denominated this part 
the clypeus, in which he has been followed by most mo- 
dern Entomologists. You may therefore think, perhaps, 
that I have here unnecessarily altered a term so gene- 
rally adopted, and expect that I assign some sufficient 
reasons for such a change. I have before hinted that 
there is good ground for thinking that the sense of smell 
in insects resides somewhere in the vicinity of this part; 
and when I come to treat of their senses, I shall produce 
at large those arguments that have induced me to adopt 
this opinion : and if I can make out this satisfactorily, 
you will readily allow the propriety of the denomination. 
I shall here only state those secondary reasons for the 

a Plates VI. VII. XXVII. a. 



476* EXTERNAL ANATOMY OF INSECTS. 

term, which, in my idea, prove that it is much more to 
the purpose than clypeus. This last word was originally 
applied by Linne in a metaphorical sense to the ample 
covering of the head of the Scarabaidce, and the thoracic 
shield of Silpha, Cassida, Lampyris, and Blatta : in all 
which cases there was a propriety in the figurative use 
of it, because of the resemblance of the parts so illustrated 
to a shield. But when Fabricius (though he sometimes 
employs the term, as Linne did, merely for illustration,) 
admitted it into his orismological table, as a term to re- 
present universally the anterior part of the face of insects 
to which the labrum is attached (though in some cases 
he designates the labrum itself by this name), it became 
extremely inappropriate ; since in every case, except that 
of the Scarabceida:, the part has no pretension to be 
called a shield ; — so that the term is rather calculated to 
mislead than illustrate. This impropriety seems at length 
to have struck M. Latreille, since in a late essay a he has 
changed the name of this part to Epistomis, a term signi- 
fying the part above the mouth. But there are reasons, 
exclusive of those hereafter to be produced concerning 
the sense of smell, which seem to me to prove that nasus 
is a preferable term; not to mention its claim of priority, 
as having been used to signify this part a century ago b . 
When we come to consider the terms for the other parts 
of the head, as lips, jatvs, tongue, eyes, temples, cheeks, 
forehead, &c. the concinnity, if I may so speak, and haiv 
mony of our technical language, seem to require that the 
part analogous in point of situation to the nose of ver-te- 

* Organisat. Exter. des Ins. 196. 

b In the Transactiom of the Royal Society, this part in Anobium 
tessellatum is so called, xxxiii. 159 — . 



EXTERNAL ANATOMY OF INSECTS. 477 

brate animals should bear the same name. And any per- 
son who had never examined an insect before, if asked 
to point out the nose of the animal, would immediately 
cast his eye upon this part : so that one of the principal 
uses of imposing names upon parts — that they might be 
more readily known — would be attained. If it is object- 
ed, that calling a part a nose that has not the sense of 
smell, supposing it to be so, might lead to mistakes — I 
would answer, that this objection is not regarded as va- 
lid in other cases : for instance, the maxilla are not ge- 
nerally used as jaws, and yet no one objects to the term ; 
because, from their situation, they evidently have an ana- 
logy to the organs whose name they bear. But enough 
on this subject — we will now consider the part itself. 

To enable you to distinguish the nose of insects when 
it is not separated from the rest of the face by an impressed 
line, you must observe that it is the terminal middle part 
that sometimes ovei'hangs the upper-lip, and at others 
is nearly in the same line with it; that on each side of it 
are the cheeks, which run from the anterior half of the 
eyes to the base of the mandibles. Just below the an- 
tennae is sometimes another part distinct from the nose, 
which I shall soon have to mention ; so that the nose 
must not be regarded as reaching always nearly to the 
base or insertion of the antennae, since it sometimes oc- 
cupies only half the space between them and the upper- 
lip, which space is marked out by an impressed line. 
But you will not always be left at such uncertainty when 
you want to ascertain the limits of the nose ; for it is in 
many cases a distinct piece, separated by an elevated or 
impressed line from the rest of the face. This separa- 
tion is either partial or universal. Take any species of 



473 EXTERNAL ANATOMY OF INSECTS. 

the genera Copris, Onitis, or Ateuchus, and you will see 
the nose marked out in the centre of the anterior part oi 
the face by two elevated lines, forming nearly a triangle 
and bounded by the horn a . Or take a common wasp or 
hornet, and you will find a similar space, though ap- 
proaching to a quadrangular figure, marked out by im- 
pressed lines b . In Rhagio and Sciara, two Dipterous ge- 
nera, this impression is so deep as to look like a suture. 
Between these lines, in those cases, is included what I 
call the nose. As to substance, in general it does not dif- 
fer from the rest of the head; but in the Cleridee it is 
almost membranous. You must observe, that in all these, 
what at first sight appears to be the termination of the 
front, is not the nose, but the narrow depressed piece 
that intervenes between it and the lip. With regard to 
its clothing, it is most commonly naked, but in some ge- 
nera it is covered with hair; in Crabro F. often with 
golden or silver pile, which imparts a singular brilliance 
to the mouth of the insects of that genus : M. Latreille 
supposes that the brilliant colours of the golden-wasp 
(Chrysis L.) may dazzle their enemies, and so promote 
their escape c ; the brilliance of the mouth of the Cra- 
bro may on the contrary at first dazzle their prey for a 
moment, so as to prevent their escape. The form of the 
nose, where distinct from the rest of the face, admits of 
several variations : thus in the Staphylinidce and Cleridte 
it is transverse and linear; in Copris it is triangular, with 
the vertex of the triangle truncated ; in Vespa Crabro it 
is subquadrate and sinuated. In many Heteromerous 

a Plate XXVII. Fig. 4. a. b Plate VII. Fig. 2. a. 

e Observ. Nouv. sup les Hymennptcres {Ann. du Mus.) 5. 



EXTERNAL ANATOMY OF INSECTS. 479 

beetles a it is rounded posteriorly : in Pelecotma, a new 
genus in this tribe, related to Asida, there is a deep an- 
terior sinus ; in Blaps the anterior margin is concave ; 
in Cetonia h Brownii, and atropunctata (forming a distinct 
subgenus), it is bifid: it varies in the ScarabceicLe, in 
some being bidentate, in others quadridentate, and in 
others again sexdentate, including the cheeks : in Myla- 
bris, a kind of blister-beetle, it is transverse and nearly 
oval ; in Lamia, a capricorn-beetle, it represents a paral- 
lelogram; and in most Orthoptera it is orbicular: in TeU 
tigonia F. it is prominent, transversely furrowed, and di- 
vided by a longitudinal channel : in Otiocems K. it pre- 
sents the longitudinal section of a cone c : in the Diptera 
Order, with the exception of the TipulidcB and some 
others, in which it unites with the cheeks, &c. to form a 
rostrum, the nose in general, as to form, answers to its 
name, resembling that of many of the Mammalia: in 
some of the Asilidce it is very tumid at the end, and ter- 
minates in a sinus, to permit the passage of the proboscis 
to and fro : in many of the Syrphida, &c. it is first flat 
and depressed, and then is suddenly elevated, so as to 
give the animal's head the air of that of a monkey : in 
some tribes, as Rhingia, Nemotelus, Eristalis, &c, in 
conjunction with the cheeks itjbrms a conical rostrum: 
in Tabanus bovinus, and other horse-flies, it terminates 
in three angles or teeth. Many more forms might be 
mentioned, but these will suffice to give you a general 
idea of them. In size and proportions the nose also va- 

a Those beetles whose posterior pair of tarsi have only four joints, 
and the two anterior five, are so called. 

b Kirby in Linn. Trans, xii. 464. /. xxiii./. 6. 
c Ibid. xiii. t.'i.f. \.b. 



480 EXTERNAL ANATOMY OF INSECTS. 

ries. It is frequently, as in Tettigonia, the most conspi- 
cuous part of the face, both for size and characters ; but 
in the Staphylinidce it is very small, and often scarcely 
discernible, being overshadowed by its ample front : and 
it may be observed in general, that when the antennae 
approximate the mouth, as in this genus and many others, 
the front becomes ample, and the nose is reduced to its 
minimum : but when they are distant from the mouth, the 
reverse takes place; and the nose is at its maximum and 
the front at its minimum. Mutilla, Myrmecodes, Scolia, &c. 
in the Hymenoptera, are an example of the former; and 
the Pompilidce, Sphecidce, Vespidce, &c. of the latter. In 
Myopa buccata, Sec. its length exceeds its width ; but more 
commonly the reverse takes place. The circumscription of 
the nose also deserves attention. It is usually terminated 
behind by the front (from), or, where it exists, by the post-*- 
nasus, in the sides by the cheeks, and anteriorly by the la~ 
brum. But this is not invariably the case; for in the Cimi- 
eidte, in which the cheeks form the bed of the Promuscis, 
the front embraces it on each side by means of two lateral 
processes, that sometimes meet or lap over each other 
anteriorly, which gives the nose the appearance of being 
insulated ; but it really dips below these lobes to join the 
labrum. This structure you may see in Edessa F., and 
many other bugs. This part sometimes has its arms. 
Thus in Copris, and many DynastidcE, the horns of the 
head seem, in part at least, to belong to this portion of 
it ; in Tipula oleracea (the crane-fly), &c. it terminates 
before in a horizontal mucro. In Osmia cornuta, a kind 
of wild-bee, each side of the nose is armed with a ver- 
tical horn. The margin of the nose in most Lamellicorn 
insects, though mostly level, curves upwards. 



EXTERNAL ANATOMY OF INSECTS. 481 

I am next to mention a part of the nose which me- 
rits a distinct name and notice, which I conceive in some 
sort to be analogous to the nostrils of quadrupeds, and 
which I have therefore named the Rhinarium or nostril- 
piece. I had originally distinguished it by the plural term 
naves, nostrils; but as it is usually a single piece, I thought 
it best to denote it by one in the singular. When I 
treat of the senses of insects, I shall give you my reasons, 
as I have before said, for considering this part as the 
organ of scent, or connected with it, which you will then 
be able to appreciate. I shall only here observe, that the 
piece in question is in the usual situation of the nostrils 
— between the nose and the lip. In a large number of 
insects this part may be regarded as nearly obsolete; 
or at least it is merely represented by the very narrow 
membranous line that intervenes between the nose and 
the lip and connects them ; which, as in the case of the 
head of Harpali before noticed, may be capable of ten- 
sion and relaxation, and so present a greater surface to 
the action of the atmosphere. But I offer this as mere 
conjecture. In the lady-bird (Coccinella) this line is a 
little wider, and becomes a distinct Mhinarium ; as it 
does also in Geotrupes. With respect to its insertion, 
the rhinarium is a piece that either entirely separates 
the nose from the lip, or only partially : the former is 
the most common structure. It is particularly remark- 
able in a New Holland genus of chafers (Anoplognat/ms 
Leach). In A. viridicenens it is very ample, and forms 
the under side of the recurved nose, so that a large space 
intervenes between the margin of the latter and the base 
of the labrum. In Macropus Thunb., of the Capricorn 
tribe (Cerambyx L.), the nostril-piece, which forms a 

vol. III. 2 1 



482 EXTERNAL ANATOMY OF INSECTS. 

distinct segment, is narrower than the nose, and the 
upper-lip than the nostril-piece, forming as it were a 
triple gradation from the front to the mouth. Again, in 
others the part in question is received into a sinus of the 
nose. This is the case with the dragon-flies (Libellulina), 
in which this sinus is very wide ; in the burying-beetle 
(Necrophorus) % in some species of which it is deep but 
narrow ; and in a species of Tenebrio from New Holland, 
which perhaps would make a subgenus. If you examine 
with a common glass any of the larger rove-beetles (Sta- 
phylinidce), you will find that the nose itself seems lost in 
the nostril-piece, both together forming a very narrow 
line across the head above the labrum, without any ap- 
parent distinction between them; but if you have recourse 
to a higher magnifier, you will find this divided into an 
upper and lower part, the former of the hard substance 
of the rest of the head, and the latter membranous. I 
once was of opinion that the prominent transversely fur- 
rowed part, so conspicuous in the face of Tettigonia F. b , 
was the front: but upon considering the situation of this, 
chiefly below the eyes and antennas, and comparing it 
with the analogous piece in Fulgora laternaria and other 
insects of the Homopterous section of the Hemiptera, I 
incline to think that it represents the nose, and that the 
longitudinal ridge below it is the nostril -piece c . In the 
Heteropterous section it is merely the vertical termina- 
tion of their narrow nose. In other insects again, this 
part approaches in some measure to the common idea of 
nostrils ; there being two, either one on each side the 
nose, or two approximated ones. If you catch the first 
humble-bee that you see busy upon a flower, you will 
A Plate VI. Fig. 10. g'. ■> Ibid. Fig. 7. a. c Ibid. g'. 



EXTERNAL ANATOMY OF INSECTS. 483 

discover a minute membranous protuberance under eacli 
angle ot the nose. Something similar may be observed 
in some species of Asilus L. In the Ortkoptera, espe- 
cially in Blatta, Phasma, and some Locusta?, two roundish 
or square pieces, close to each other on the lower part 
of the nose, represent the nostrils a . — With regard to 
substance, in the chafer- tribes, at least those that feed 
on leaves or living vegetable matter, as the Melolon- 
thidce, Anoplognatludce, and in many other insects, the 
rhinarium is of the same substance with the rest of the 
head; but in Macropus Thunb., Staphylinus, Necrophorus, 
&c, it consists of membrane. 

ii. Postnasus b . — This is a part that appears to have 
been confounded by Entomologists with the front of in- 
sects; in general, indeed, it may be regarded as included 
in the nose, and does not require separate notice : but 
there are many cases in which it is distinctly marked out 
and set by itself, and in which it forms a useful diagno- 
stic of genera or subgenera. There is a very splendid 
and beautiful Chinese beetle, to be seen in most collec- 
tions of foreign insects (Sagra purpurea), in which this 
part forms a striking feature, and helps to distinguish the 
genus from its near neighbour Donacia. If you examine 
its face, you will discover a triangular piece, below the 
antennas and above the nasus, separated from the latter 
and from the front by a deeply-impressed line : this is the 
postnasus or after-nose. Again : if you examine any spe- 
cimens of a Hymenopterous genus called by Fabricius 
Prosojns (Hylceus Latr.), remarkable for its scent of 
baum, you will find a similar triangle marked out in a 

1 Plate VI. Fig. 4. g'. b Plates VI. VII, b. 

2 i 2 



484- EXTERNAL ANATOMY OF INSECTS, 

similar situation a . In many Coleopterous insects, besides 
Sagra, you will discover traces of the part we are consi- 
dering : as in Anthia, Dytiscus, and several others of the 
Predaceous beetles. In Cistela it is larger than the nose 
itself; but it is more conspicuous in the Orthoptera, par- 
ticularly in Locusta {Gryllus F.), in which it is the space 
below the antennas, distinguished by two or four rather 
diverging ridges b . In the Libellulina, Myrmeleonina, 
&c. it is a distinct transverse piece. In Dasyga Latr., 
a kind of bee, it is armed with a transverse ridge or horn 
— But enough has been said to render you acquainted 
with it ; I shall therefore proceed to the next piece. 

hi. Frons c . — The Front of insects may be denomi- 
nated the middle part of the face between the eyes, 
bounded anteriorly by the nose, or after-nose, where it 
exists, and the cheeks ; laterally by the eyes ; and poste- 
riorly by the vertex. Speaking properly, it is the region 
of the antenna ; though when these organs are placed 
before the eyes, under the margin of the nose, as in many 
Lamellicorn and Heteromerous beetles, they seem to be 
rather nasal than frontal. This part is often elevated, 
as in the elastic beetles (Elater), whose faculty of jump- 
ing, by means of a pectoral spring, has been related to 
you d . In Anthia, a Predaceous beetle, it has often three 
longitudinal ridges. In many of the Capricorn beetles 
{Cerambyx L.), it is nearly in the shape of a Calvary 
cross, with the arms forming an obtuse angle, and then 
terminating at the sinus of the eyes in an elevation for 
the site of the antennae. In the ants also (Formicidce), 

a Kirby Mon. Ap. Angl. i. t. i. Melitta. *. b.f. 3. 

b Plate VI. Fig. 4. b. <= Plates VI. VII, c. 

J Vol. II. y.. 317—, 



EXTERNAL ANATOMY OF INSECTS. 485 

the front is often elevated between those organs. In 
Ponera, one tribe of them, this elevation is bilobed, 
and receives between its lobes the vertex of the post- 
nasus. In the hornet ( Vespa Crabro) the elevation is a 
triangle, with its vertex towards the mouth. In Sagra 
it is marked out into three triangles, the postnasus mak- 
ing a fourth, with the vertexes meeting in the centre. 
In the Dynastidce and Scarabdcid.ee the horns are often 
frontal appendages,- as is that of Empusa Latr., a leaf- 
insect, and probably those of Sphinx latropkdeF., which 
affords a singular instance of a horned Lepidopterous one. 
Sometimes it is an ample space, reducing the nose to a 
very narrow line, as in the Stapkylinida, or sending 
forth a lobe on each side, as before mentioned, which 
embraces the nose. In a species of bug from Brazil, re- 
lated to Aradus F., these lobes are dilated, foliaceous, 
and meet before the nose, so as to form a remarkable 
extended frontlet to the head. In others this part is ex- 
tremely minute : thus in many male flies and other in- 
sects, as the Libellulina, where the eyes touch each other, 
the front is cut off from the vertex and reduced to a small 
angle. In the female flies the communication with the ver- 
tex is kept open, and the front consequently longer. In 
the horse-flies ( Tabanidde), in Hcematopota, and Hepta- 
toma, the frontal space is wider than in the rest of that 
tribe. Many of these are distinguished by a levigated 
area behind the antennae in the part we are treating of. 
In the Libellulina, and in the drone-bee, whose eyes are 
confluent, the stemmata are in the front. In many Or- 
thoptera also, as Locusta Leach, one of them is below 
the antenna? ; and in the lanthorn-fly tribe (Fulgoridce), 
both these organs, which are situate between them and 



486 EXTERNAL ANATOMY OF INSECTS. 

the eyes, as they do also in Truxalis, appear to be in 
it a . In this tribe the rostrum is an elongation of the 
part in question ; and perhaps you would think at first 
that what I have considered as the nose in Tettigonia F. 
was also a tendency to this kind of rostrum ; but if you 
examine the great lanthorn-fiy (Fulgora latemaria), you 
will find besides, at the lower base of the lanthorn, a tri- 
angular piece analogous to the nose of Tettigonia, and 
below it another representing its nostril-piece: — the hori- 
zontal part of the nose in that genus may perhaps be re- 
garded as part of the front. In Truxalis F. the face 
consists of a supine and prone surface, and the latter is 
composed of the front, after-nose, nose, and organs of the 
mouth. I may notice here a most remarkable and singu- 
lar tribe of bugs, of which two species have been figured 
by Stoll b : in these the head, or rather those parts of it that 
we have now been describing, the nose, namely, the after- 
nose, and front, are absolutely divided longitudinally in 
two, each half having an eye and antenna planted in it ; 
or perhaps, as it is stated to be divided in one instance to 
the commencement of the promuscis, the nose is left in- 
tire, and dips down, as in cases before alluded to : so that 
in this the nose appears to leave the lobes of the front, 
which in others embrace its sides. 

iv. Vertex c . — We now come to the vertex, or crown 
of the head ; which is situated behind the front, and, 
except where the communication is intercepted by con- 
fluent eyes, adjoins it. It is laterally bounded by the 
hind part of the eyes and the temples ; and posteriorly, 

3 Plate XXVI. Fig. 41. i. 

b Stoll Punaises, t. xxxix. /. 279, 280. 

c Plates VI. VII. XXVI. d. 



EXTERNAL ANATOMY OF INSECTS. 487 

where that part exists, by the occiput. The vertex may 
be denominated the ordinary region of the stemmata : 
for though in several cases, as we have just seen, one or 
more of them are planted in the front; yet this in the great 
majority, especially in the Hymenoptera, is their natural 
station. In Blatta and some other Orthoptera the poste- 
rior angle of the head is the vertex. In many dung- 
chafers of Latreille's genus Onthophagus, which are said 
to have occipital horns, as O. nutans, nuchicornis, Xi- 
phias, &c, the horn really arms the part I regard as the 
vertex. In Locusta Leach, this part is very ample, and 
in Truxalis very long ; but more generally it is small, 
and not requiring particular notice. 

v. Occiput*. — The occiput, or hind-head, is that part 
of the face that either forms an angle with the vertex 
posteriorly, or slopes downwards from it. ' It has for its 
lateral boundaries the temples, and behind it is either 
terminated by the orifice of the head, or in many cases 
by the neck. In those beetles that have no neck, as the 
Lamellicorn and Capricorn, the hind-head is merely a de- 
clivity from the vertex, usually concealed by the shield of 
the thorax, very lubricous, to facilitate its motion in the 
cavity of that part, and at its posterior margin distin- 
guished by one or two notches, which I shall notice 
hereafter, for the attachment of the levator muscles : but 
in those beetles or other insects that have a neck, or a 
versatile head, the occiput forms an angle with the vertex, 
often rounded, and sometimes acute. This structure may 
be seen in Latreille's Trachelides, and several other bee- 
tles. In the Hymenoptera, Diptera, and others with a 

« Plates VI. VII. e. 



488 EXTERNAL ANATOMY OF INSECTS. 

versatile head, the part now under consideration curves 
inwards from the vertical line, so as with the temples and 
under parts of the head to form a concavity adapted to 
its movement upon the trunk. 

vi. Gence a . — The cheeks of insects (Gence) usually sur- 
round the anterior part of the eyes, and lie between them 
and the mandibles or their representatives. Where they 
approach the latter, as in the Predaceous beetles (Cicin- 
dela, Carabus L. &c), they are very short, and of course 
longer where the eyes are further removed from the 
month; as in the Rhyncophorous beetles [Curculig L.), 
where they form the sides of the rostrum, and often con- 
tain a channel which receives the first joint of the anten- 
nas, when they are unemployed. In the Scarabceidce and 
many other Lamellicorn beetles, their separation on each 
side from the nose is marked by a ridge b ; and in the 
wasps (Vespa) by an impressed line or channel. In an 
African tribe at present arranged with Cetonia F., to 
which C. bicomis Latr. c and another, which he has named, 
I believe, C. vitticollis, belong, the cheeks are porrected 
on each side of the mouth into a horizontal horn. These 
horns have at first the aspect of a pair of open mandibles. 
In the magnificent Goliathi Lam., the horns of the male 
are rather a process of the cheek than of the nose. In 
Alurnus, Hispa, and other beetles, these parts, by their 
elevation and conjunction with the lower side of the 
head, form a kind of fence which surrounds and protects 
the oral organs ; in many Cimicidce, by a similar eleva- 
tion of the cheeks, the bed of the promuscis is formed. 

1 Plates VI. VII. f. h Plate XXVII. Fig. 4. f. 

c Cuv. Regne Animal iii. t, xiii f. 4. 



EXTERNAL ANATOMY OF INSECTS. 489 

In the Homopterous Hemiptera they run parallel nearly 
with the rhinarium or nostril-piece. In the Hymenoptera 
they are almost always ample, but they are confined to 
the lower side of the eye. In Sir ex Gigas, and others of 
that genus, the cheek at the base of the mandible is di- 
lated so as to form a rounded tooth below it. In the 
Capricorn-beetles it is considerable, and sometimes ter- 
minates, at the base of the mandible, in two or three 
notches. In Scaurus and Eurychora, darkling-beetles, 
the cheek below projects into a lobe that covers the base 
of the maxilla. But the animal distinguished by the 
most remarkable cheeks is a species of Pliryganea L. 
{Pliryganea personata Spence) ; for from this part pro- 
jects a spoon-shaped process, which curves upwards, and 
uniting with that of the other cheek, forms an ample mask 
before the face, the anterior and upper margin of which, 
in the insect's natural state, are closely united ; and the 
posterior part being applied to the anterior part of the 
eye, causes the face to appear much swoln. It looks as 
if it was a single piece ; but upon pressing the thorax it 
opens, both above and in front, into two parts, each con- 
vex without and hollow within, and each having attached 
to its inside a yellow tuft of hair resembling a feather. 
The use of this machinery at present remains a my- 
stery a . 

vii. Tempora b . — The temples ( Tempora) are merely 
a continuation of the cheeks to the posterior limit of the 



a This insect was taken both at Matlock and Exmonth. The body 
and thighs are of a light-brown, wings testaceous, legs pale ; antennae 
between setaceous and filiform, two-thirds the length of the body ; 
first joint not much thicker than the rest, 

" I'LATES VI. VII. R. 



490 EXTERNAL ANATOMY OF INSECTS. 

head, forming its sides and posterior angles, and includ- 
ing the hinder part of the eyes, the vertex, and the occi- 
put. They seldom exhibit any tangible character, ex- 
cept in certain ants (Atta Latr.), in which their angle 
terminates in one or two strong spines, giving the ani- 
mal a most ferocious aspect; and in that remarkable ge- 
nus Corydalis they are armed below with a tooth or point, 
which was not overlooked by De Geer a . 

viii. Oculi b . — I must now call your attention to organs 
of more importance and interest, and which indeed in- 
clude a world of wonders : I mean the eyes ( Oculi) of 
insects. These differ widely from those of vertebrate 
animals, being incapable of motion. They may be re- 
garded as of three descriptions — simple, conglomerate, 
and compound. 

1. Simple Eyes c . We will consider them as to their 
number, structure, shape, colour, magnitude, situation, and 
arrangement. 

As to their number, they vary from two to sixteen. 
In the flea, the louse, the harvest-man [Phalangium), 
there are only a pair ; in the bird-louse of the goose 
(Nirmus Anseris), and probably in others of the same 
genus, there are four d ; in some spiders (Scytodes, Dys- 
dera, and Segestria Latr. e ), and some scorpions f , there 
are six. In the majority of spiders and Scolopendra mor- 

* De Geer iii. 561. t. xxvii./. 1. b Plates VI. VII. XXVI. h. 

<= Plate VII. Fig. 8, 9. XXVI. Fig. 43. h. 

d Viz. one on each side above, and one below. 

Walckenaer Araneides, t. v.f. 50, 52. t. viii./. 82. 

f Treviranus (Arachnid. 4.) says that Scorjno Europceus has only 
two eyes. He appears to have overlooked the two on the anterior 
side of a tubercle at each angle of the head, where they are large, 
but not conspicuous, at least in ray specimen. 



EXTERNAL ANATOMY OF INSECTS. 491 

sitans, Scorpio maurus, &c. there are eight ; and in Po- 
dura and. Sminthyrus Latr. there are sixteen a . 

As to their structure, nothing seems to have been ascer- 
tained ; probably their organization does not materially 
differ from that of one of the lenses of a compound eye ; 
which I shall soon explain to you. 

Their colour in the many is black and shining, but in 
the bird-louse of the goose they are quite white and 
transparent. In spiders they are often of a sapphirine 
colour, and clear as crystal. In Scolopendra mor sitans 
and many spiders, scorpions, and phalangia b , they ap- 
pear to consist of iris and pupil, which gives them a 
fierce glare, the centre of the eye being dark and the 
circumference paler. In the celebrated Tarantula {Ly- 
cosa Tarantula), the pupil is transparent, and red as a 
ruby ; and the iris more opaque, paler, and nearly the 
colour of amber. 

Where there are more than two, they vary in magni- 
tude. In the enormous bird-spider (Mygale avicularia) 
the four external eyes are larger than the four internal c ; 
but in the Tarantula and Sphasus, the two ox four inter- 
nal are the largest. In Clubiona and Drassus they are all 
nearly of the same size d ; and in the Micrommata family 
they are very small e . 

They vary also in shape. In Scolopendra mor sitans the 
three anterior ones are round, and the posterior one 
transverse, and somewhat triangular. In Mygale cal- 
peiana, a spider, the two smallest are round and the rest 

11 DeGeervii. t.'m. f. 8,9, 12. 

» Plate XXVI. Fig. 43. h. c Walck. Aran. t. If. 3. 

d Ibid. t. v.f. 42—48. e Ibid. t. iv.f. 41. 



492 EXTERNAL ANATOMY OF INSECTS. 

oval a . In the trapdoor or mason spider (Mygale cce- 
mentaria), the four small internal ones are round, and 
the large external ones oval b ; and those that are cir- 
cumscribed posteriorly with an impressed semicircle, are 
shaped like the moon when gibbous c . 

The situation and arrangement of simple e3'es are also 
various. In many they are imbedded, as usual, in the 
head ; but in the little scarlet mite, formerly noticed d , 
( Trombidium holosericeum), they stand upon a small foot- 
stalk e : the hairiness of this animal might otherwise have 
impeded its sight. In spiders they are planted on the 
back of the part that represents the head, sometimes four 
on a central elevation or tubercle, and the remaining 
four below it — as in Lycosa,- sometimes the whole eight 
are on a tubercle, as in Mygale ; and sometimes, as in 
the common garden-spider (Epeira Diadema), upon 
three tubercles, four on the central one and two on each 
of the lateral ones. Other variations in this respect might 
be named in this tribe. In the scorpions a pair are placed 
one on each side, on a dorsal tubercle, and the other four 
or six on two lateral ones of the anterior part of the 
head f . In the Phalangida the frontal eyes of the scor- 
pion cease, and only a pair of dorsal ones are inserted 
vertically in the sides of a horn or tubercle, either bifid 
or simple, often itself standing upon an elevation which 
emerges from the back of the animal s. If their eyes 
were not in a vertical and elevated position, the sight of 

* Walck. Aran. t. If. 2. b /jy. ,;_ \^ 7> 

c Ibid. t. u.f. 18, 20. d Vol. I. p. 323. 

e De Geer vii. 138. t. viii. f. 15. y y, f Ibid. t. xl./. 3. oo,yy. 

g Plate XXVI, Fig. 43. h. 



EXTERNAL ANATOMY OF INSECTS. 493 

these insects would be very limited ; but by means of the 
structure just stated, they get a considerable range of sur- 
rounding objects, as well as of those above them. With 
regard to the arrangement of the eyes we are consider- 
ing, it varies much. Sometimes they are placed nearly 
in the segment of a circle, as in those spiders that have 
six eyes only, before noticed a ; sometimes in two straight 
lines b ; at others in two segments of a circle c ; at others, 
in three lines d , and at others in four e . Again, in some 
instances they form a cross, or two triangles f ; in others, 
two squares s ; in others, a smaller square included in a 
large one h ; in others, a posterior square and two anterior 
triangles ' ; sometimes a square and two lines. Though 
generally separate from each other, in several cases two 
of the eyes touch k ; and in one instance three coalesce 
into a triangle '. But it would be endless to mention all 
the variations, as to arrangement, in the eyes of spi- 
ders. 

2. Conglomerate Eyes m differ in nothing from simple 
eyes, except that instead of being dispersed they are col- 
lected into a body, so as at first sight to exhibit the ap- 
pearance of a compound eye : — they are, however, not 
hexagonal, and are generally convex. They occur in 

a Segestria perjida, Walck. Aran. t. v.f. 52. &c. 

b Tetragnatha and Latrodectes, Ibid. I. vii./. 64. and /. ix.f. 84. 

c Nyssus coloripes, Ibid. t. vi-f. 58. 

d Bolomeda, Ibid. t. u.f. 18, 20. 

e Sphasus, Ibid. t. m.f- 24. 

f My gale avicidaria, Ibid. t. \.f. 3. 

e Sparasus, Ibid. t. iv. /. 41. Plate XXVI. Fig. 37- 

b Eresus, Ibid. t. m.f. 26. l Storena, Ibid. t. ix.f. 86. 

x Argyroncta, Ibid.f. 88. ' Pholcus, Ibid, t. viii./. 80. 

m Plate XIII. Fig. 11. 



494 EXTERNAL ANATOMY OF INSECTS. 

Lepisma, the Tulidte, and several of the Scolopendridce. 
In Scolopendra forjicata the eye consists of about twenty 
contiguous, circular, pellucid lenses, arranged in five 
lines, with another larger behind them, as a sentinel or 
scout, placed at some little distance from the main body. 
In the common millepede (lulus terrestris) there are 
twenty-eight of these eyes, placed in seven rows, and 
forming a triangle, thus .. : & — the posterior row con- 
taining seven lenses, the next six, and so on, gradually 
losing one, till the last terminates in unity. Each of 
these lenses is umbilicated, or marked with a central de- 
pression. In Craspedosoma Leach, you will find a similar 
formation. In Glomeris zonata, a kind of wood-louse 
that rolls itself into a ball, the lenses are arranged in a 
line curved at the lower end, with a single one by itself 
at the posterior end on the outside; they are oblong and 
set transversely, and their white hue and transparency 
give them the appearance of so many minute gems, espe- 
cially as contrasted with the black colour of the animal 3 . 
Between these eyes and the antennae is another trans- 
verse linear white body, but opaque, seemingly set in a 
socket, and surrounded by a white elevated line, like the 
bezel of a ring. Whether it is an eye, or what organ, I 
cannot conjecture b . Its aspect is that of a spiracle. 

3. Compound Eyes z . — These are the most common kind 
of eye in hexapod insects, when arrived at their perfect 
state ; in their larva state, as we have seen, their eyes 
being usually simple d ; except, indeed, those whose me- 
tamorphosis is semicomplete, which have compound eyes 

* Plate XXIX. Fig. 1 1. h. •> Ibid. a. 

c Plate XIIT. Fig. 10. <i See above, p. 117— 



EXTERNAL ANATOMY OP INSECTS. 495 

in every state. — In considering compound eyes, I shall 
advert to their structure, number, situation, Jigure, cloth- 
ing, colour, and size. 

As to their structure, — when seen under the microscope 
they appear to consist usually of an infinite number of con- 
vex hexagonal pieces. If you examine with a good glass 
the eye of any fly, you will find it traversed by numberless 
parallel lines, with others equally numerous cutting them 
at right angles, so as apparently to form myriads of little 
squares, with each a lens of the above figure set in it. The 
same structure, though often not so easily seen, obtains in 
the eyes of Colcoptera and other insects. When the eye 
is separated and made clean, these hexagons are as clear 
as crystal. Reaumur fitted one eye to a lens, and could 
see through it well, but objects were greatly multiplied 3 . 
In Coleopterous insects they are of a hard and horny 
substance ; but in Diptera, &c. more soft and membra- 
nous. The number of lenses in an eye varies in different 
insects. Hooke computed those in the eye of a horse- 
fly to amount to nearly 7,000 b ; Leeuwenhoeck found 
more than 12,000 in that of a dragon-fly c ; and 17,325 
have been counted hi that of a butterfly d . But of all in- 
sects they seem to be most numerous in the beetles of 
Mr. W. S. MacLeay's genus Dynastes. In the eyes of 
these the lenses are so small as not to be easily discover- 
able even under a pocket microscope, except the eye has 
turned white e : it is not, therefore, wonderful, that Fabri- 

3 Reaum. iv. 245. b Microgr. 176. 

c Epht. Mar. 6. 1717- d Amceri. Academ. vii. 141. 

e I possess a specimen in which the eye is partly black and partly 
white : the lenses are invisible in the black part, but very visible in 
the white. 



49G EXTERNAL ANATOMY OF INSECTS. 

cius should call these eyes simple a . In some insects, how- 
ever, as in the Slrcpsiptera Kirby, the lenses are not nu- 
merous : in Xe?ws they do not exceed fifty, and are di- 
stinctly visible to the naked eye b . These lenses vary in 
magnitude, not only in different, but sometimes in the 
same eyes. This is the case hi those of male horse-flies 
and flies, those of the upper part of the eye being much 
larger than those of the lower c . The partitions that 
separate the lenses, or rather bezels, in which they are set, 
are very visible in the eyes just mentioned, and those of 
Xenos ; but in many insects they are only discernible at 
the intersecting lines of separation between the lenses. 
In hairy eyes, such as those of the hive-bee, the hairs 
emerge from these septa. Every single lens of a com- 
pound eye may be considered as a cornea, or a crystal- 
line humour, it being convex without and concave within, 
but thicker in the middle than at the margin : it is the 
only transparent part to be found in these most remark- 
able eyes. Immediately under the cornea is an opaque 
varnish, varying according to the species, which pro- 
duces sometimes in one and the same eye spots or bands 
of different colours. These spots and bands form a di- 
stinguishing ornament of many of the Tabani and other 
flies. And to this varnish the lace-winged flies (Hemc- 
robius, &c.) are indebted for the beautiful metallic hues 
that often adorn them. When insects are dead, this 
varnish frequently loses its colour, and the eye turns 
white : hence many species are described as having white 
eyes which when alive had black ones. The consistence 



a Philos. Entomolog. 19. ^ p LATE XXVI. Fig. 38. 

e Hooke Microgr. schem. xxiv. 



EXTERNAL ANATOMY OF INSECTS. 497 

of this covering is the same with that of the varnish of 
the choroid in the eyes of vertebrate animals ; but it en- 
tirely covers the underside of the lens, without leaving 
any passage for the light. Below this varnish there are 
numbers of short white hexagonal prisms a , every one of 
which enters the concavity of one of the lenses of the 
cornea, and is only separated from it by the varnish just 
described : this may be considered as the retina of the 
lens to which it is attached ; but at present it has not been 
clearly explained how the light can act upon a retina of 
this description through an opaque varnish. Below this 
multitude of threads (for such the bodies appear), per- 
pendicular to the cornea, is a membrane which serves 
them all for a base, and which consequently is nearly pa- 
rallel with that part. It is very thin, of a black colour, 
not produced by a varnish ; and in it may be seen very 
fine white tracheae, which send forth branches still finer, 
that penetrate between the prisms of the cornea : this 
membrane may be called the choroid. Behind this is a 
thin expansion of the optic nerve, which is a true nerv- 
ous membrane, precisely similar to the retina of red- 
blooded animals. It appears that the white pyramidal 
threads which form the retina of each lens are sent forth 
by this general retina, and pierce the choroid by a num- 
ber of almost imperceptible holes b . From this descrip- 
tion it appears that the eyes of insects have nothing cor- 
responding with the uvea or humours of those of verte- 
brate animals, but are of a type peculiar to themselves. 
Having explained to you the wonderful and complex 

a Plate XXIII. Fig. 3. 

b Cuvier Anat. Compar. ii. 442—. Compare Swummertlam Bibl. 
Nat i. 211. t. xx. /. 45. 

VOL. III. 2 K 



498 EXTERNAL ANATOMY OF INSECTS. 

structure with which it has pleased the Creator to di- 
stinguish the organs of vision of these minute beings, 
proving, what I have so often asserted, that when ani- 
mals seem approaching to nonentity, where one would 
expect them to be most simple, we find them in many 
cases most complex, I shall now call your attention to the 
next thing I am to consider — the number of the eyes in 
question. Most insects have only two s but there are se- 
veral exceptions to this rule. Those that have occasion 
to see both above and below the head, the eyes of all 
being immovable, must have them so placed as to enable 
them to do this. This end is accomplished in many 
beetles, for instance Scarabaus L., Helceus Latr., &c, by 
having these organs fixed in the side of the head, so that 
part looks upward and part downward ; but in others 
four are given for this purpose. If you examine the 
common whirlwig [GyrinusNatator) that I have so often 
mentioned a , which has occasion, at the same time, to 
observe objects in the air and in the water, you will find 
it is gifted with this number of eyes. Lamia Tornator 
{Cerambyx tetrophthalmus Forst.) and some others, of 
which I make a genus, under the appellation of Te- 
trops, are also so distinguished. In these insects, one 
eye is above and the other below the base of the anten- 
nae ; in fact, in these the canthus, instead of dividing the 
eye partially, as in the other Capricorn-beetles, runs quite 
through it at considerable width b . In Byssonotus Mac- 

a Vol. II. p. 4. 364, &c. 

b Plate XXVI. Fig. 36. h. Fabricius, and after him Olivier, 
though both quote Forster, regard one of these eyes in Lamia Tor- 
nator as a spot; but they could not have examined it attentively. 
Saperda prceusta F. has also four eyes. 



EXTERNAL ANATOMY OF INSECTS. 499 

Leay (Lucanus fiebulosus K.) the eye appears also to be 
divided in two by the canthus. In the Neuroptera Order 
there is more than one instance of the same kind. In 
Ascalaphus there are two considerable eyes on each side 
of the head, which, though clearly distinct, meet like 
those of many male flies and the drone. The male, like- 
wise, of more than one species of Ephemera, besides the 
common lateral eyes and the stemmata on the back of 
the head, have a pair of compound eyes on the top of a 
short columnar process a . In the Hemiptera Order, also, 
an instance occurs of four eyes in the genus Aleyrodes b . 
Amongst the vertebrate animals, there is an example of 
eyes with two pupils in Anableps, a genus of fishes c , but 
no vertebrate animal has four of these organs. That 
many insects should have more than two eyes, will not 
seem to you so extraordinary as that any should be found 
that, like the Cyclops of old, have only one. There is, 
however, an insect, before celebrated for its agility d 
[Machilis polypodia Latr.), which has a single eye in its 
forehead; or we may say, its eyes are confluent, without 
any line of distinction between them except a small notch 
behind. Now that I am treating of the number of eyes, 
I must not forget to observe to you, that in some insects 
no eyes at all have been discovered. In Polydesmus com- 
planatus, on each side of the head there is an eye-shaped 
portion separated by a suture, in which under a power- 
ful lens I cannot satisfy myself that I can discern any 
thing like the facets that usually distinguish compound 
eyes. In Geophilus electricus, another myriapod, they 

* Plate XXYI. Fig. 39. b. 

b Latreille Gen. Crust, et Ins. iii. 73. c 2V. Diet. a" Hist. Nat. i. 479. 

* Vol. II. 320. 

2 K 2 



500 EXTERNAL ANATOMY OF INSECTS. 

certainly do not exist a . Whence we may conclude, as 
was before observed b , that the faculty of emitting light 
is rather given it as a means of defence than to guide it 
in its path. 

The situation of compound eyes differs in different 
tribes. In some, as in the Staphylinida, they are planted 
laterally in the anterior part of the head ; in others, the 
Carabi &c, in the middle ; in others again, Locusta 
Leach &c, in the posterior part. In some, their station 
is more in the upper surface, either before or behind ; so 
that a very narrow space separates them, or perhaps none 
at all. Instances of this position of the eyes occur in a 
minute weevil (Ramphus Clairv. c ), and many Diptera, 
&c. Of those that form an union on the top of the head, 
some are placed obliquely, so as to leave a diverging 
space below them, as in many Libellulina d , the drone c , 
&c. Others, as Atractocerus, in which the eyes occupy 
nearly the whole head, and unite anteriorly, have this 
diverging space above their conflux. In Rhina barbiro- 
stris Latr., another kind of weevil, they are confluent 
below the head, at the base of the rostrum, and a very 
narrow interval separates them above. In a large num- 
ber of the Heteromerous beetles, they are set transversely, 
in the Capricorn ones longitudinally. Their surface, 
when they are lateral, has usually two aspects, oneprone 
to see below, the other supine to see above. In general 
the eyes are situated behind the antennae, so that their 
position, whether it shall be anterior or posterior, de- 
pends upon that of those organs. Often, indeed, as in 

» De Geer vii. 562. i> Vol. II. p. 228. 

c Ent. Helvet. i. t. xii. «' Plate VI. Fig. 10. 

t Kirby Mon. Ap. Angl. i. t. xi. Apis. **. e. 1./. 2. 



EXTERNAL ANATOMY OF INSECTS. 501 

the last-named beetles, part of the eye is behind and part 
before the antennae ; but except where there are four 
eyes, as in Tetrops, they are never placed before or below 
them. 

Though the eyes of insects are generally sessile, yet to 
give them a wider range they are sometimes, but it rarely 
occurs, placed, like those of many Crustacea, on a foot- 
stalk, but not a moveable one. An instance of this in cer- 
tain male Ephemera has already been mentioned. In the 
Hemiptera De Geer has figured two species of bugs 
( Cimicidae) that are so circumstanced a ; as are also all 
the known Strepsiptera K., though in these the footstalk 
is very short b : but the most remarkable example of co- 
lumnar eyes is afforded by that curious Dipterous genus 
Diopsis, in which both eyes and antennae stand upon a 
pair of branches, vastly longer than the head, which di- 
verge at a very obtuse angle from its posterior part c . 

In their figure eyes vary much. Sometimes they are so 
prominent as to be nearly spherical : this is the case with 
some aquatic bugs, as Manatra, Hydrometra, and several 
male Ephemera d . Very often they are hemispherical, as 
in the tiger-beetles [Cicindela L.), and the clocks or dors 
[Carabus L.); but in a large number of insects they are 
flat, and do not rise above the surface of the head. — 
"With regard to their outline, they are often perfectly 
round, as in many weevils; oval, as in various bees; 



a De Geer iii. t. xxxiv. /. 17, 18, 24. oo. 

b Mon. Ap. Angl. i. t. xiv. no. 11./. 1./. Linn. Trans, xi. t. ix. 
/.lO.d. 

c Plate XIII. Fig. 9. Fuessly Archiv. t. vi. 

d Schellenberg Cimices t. xiii. ix. /. 1. a. De Geer ii. t. xviii. 
/• 10. 



502 EXTERNAL ANATOMY OF INSECTS. 

ovate, as in other bees (Andrena F.); triangular, as in the 
water-boatman (Notonecta). They are also often oblong, 
and occasionally narrow and linear ; as in that singu- 
lar beetle Helceus. In many of the Muscidce they form 
nearly a semicircle, or rather, perhaps, the quadrant of a 
sphere. The eyes of the Capricorn-beetles ( Cerambyx L.) 
have a sinus on their inner side, as it were, taken out of 
them ; so that they more than half surround the anten- 
nae, before which is the longest portion of them. An 
approach to this shape is mote or less observed in the 
darkling-beetles (Tenebrio L.); but in these the sinus is 
not so deep. I may under this head observe, that in 
those Ma ntidce that represent dry leaves, and some others, 
these organs usually terminate in a spine a . 

Though not distinguished by the beauty and anima- 
tion that give such interest to the eye of vertebrate ani- 
mals, and exhibiting no trace of iris or pupil, yet from 
the variety of their colours the compound eyes of insects, 
though most commonly black or brown, are often very 
striking. Look at those of one of the lace-winged flies 
that commit such havoc amongst the Aphides b , and it 
will dazzle you with the splendour of the purest gold, 
sometimes softened with a lovely green. The lenses of 
those of Xenos blaze like diamonds set in jet c . You 
have often noticed the fiery eyes of many horse-flies 
(Tabanusl^.) with vivid bands of purple and green d . 
Others are spotted e ; and Schellenberg has figured one 
( Thereva hemiptera) f , that exhibits the figure of a flower 

a Stoll Spectres, &c. t. iv.f. 14. t. x.f. 38, &c. 

b Vol. I. p. 261 — . e Linn. Trans, nhi supr. 

d Schellenberg Mouches, L xxvii.f. 1, 2.n,d. 

e Ibid. t. ix./. 3. a. < Ibid, t ii./. 2. a. 



EXTERNAL ANATOMY OF INSECTS. 503 

painted in red on a black ground. These colours and 
markings are all most vivid and brilliant in the living 
insect, and often impart that fire and animation to the 
eyes for which those of the higher animals are remark- 
able. Take one of the large dragon-flies that you see 
hawking about the hedges in search of prey, examine its 
eyes under a lens, and you will be astonished at the bril- 
liance and crystalline transparency which its large eyes 
exhibit, and by the remarkable vision of larger hexagons 
which appear in motion under the cornea, being reflect- 
ed by the retina — all which give it the appearance of a 
living eye. This moving reflexion of the hexagonal 
lenses in living insects was noticed long since in some 
bees (Nomada F., Ccelioxys Latr.) a 

Compound eyes differ greatly in their size. In some 
insects, as Atractocerus, the drone-bee, many male Mus- 
cidce, &c, they occupy nearly the whole of the head ; 
while in others, as numerous Staphylinida, Locusta 
Leach, &c, they are so small as to be scarcely larger 
than some simple eyes of spiders: and they exhibit 
every intermediate difference of magnitude in different 
tribes, genera, and species. 

Under this head I must say something of the Canthus 
of the eye ; by which I mean an elevated process of the 
cheek, which in almost all the genera of the Lamellicorn 
beetles enters the eye more or less, dividing the upper 
portion from the lower. Though usually only & process of 
the cheek, yet in the Scarabceida the whole of that part 
forms the canthus b . It only enters the eye in the Ru- 
telidcSy Cetonidce, &c. ; it extends through half of it in 

* Mori. Ap. Angl i. 148. b Plate XXVII. Fig. 4. h'. 



50* EXTERNAL ANATOMY OF INSECTS. 

Copris; it goes beyond the half in Ateuchus; and in Rys- 
sonotus MacLeay (Lucanus nebulosus K.) it quite divides 
the eye into two a , as I before observed. In Lticanus, 
Passalus &c. it projects before the eye into an angle ; in 
Lucanus femoralis nearly into a spine ; but in Lamprima 
and CEsalus it does not exist. The part, also, that enters 
the eye in the Capricorn-beetles may be regarded as a 
kind of canthiiS) though it is merely a dilatation of the 
front. 

4. Stemmata b . — Having given so full an account ot 
the kinds and structure of the ordinary eyes of insects, 
you may perhaps expect that I should now dismiss the 
subject : you would, however, have great cause to blame 
me, did I not make you acquainted with a kind of auxi- 
liary eyes with which a large portion of them are gifted ; 
I mean those pellucid spots often to be found on the poste- 
rior part of the front of these animals, or upon the vertex, 
frequently arranged in a triangle. These, Linne, from 
his regarding them as a kind of coronet, called Stem- 
mata. They have been of late denominated Ocelli ; but 
as this latter term is also in general use for the eyelets on 
the wings of Lepidoptera, I have adhered to that of the 
illustrious Swede. Neither he nor Fabricius has ex- 
pressed any opinion as to the use of these organs ; but 
Swammerdam and Reaumur were aware that they were 
real eyes. The former found that there are nerves that 
diverge to them though not easily traced, and that they 

a This circumstance proves that Mr. W. S. MacLeay is correct in 
considering this as a subgenus; but it militates against its being 
connected with Lamprima. 

" Plate VI. Fig. 4, 10. VII. Fig. 1, 2, 4. XXVI. Fig. 39-42. i. 



EXTERNAL ANATOMY OF INSECTS. 505 

have a cornea, and what he takes for the uvea a ; and the 
latter has supposed that the compound eyes and these 
simple ones have, the one the power of magnifying ob- 
jects much, and the other but little, so that the former 
are for surveying those that are distant, and the latter 
those that are near b . The same author relates some ex- 
periments that he tried with the common hive bee, by 
which he ascertained that the stemmata, as well as the 
compound eyes, were organs of vision. He first smeared 
the latter over with paint, and the animals, instead of 
making for their hive, rose in the air till he lost sight of 
them. He next did the same with the former, and placing 
the bees whose stemmata he had painted within a few 
paces of their hive, they flew about on all sides among 
the neighbouring plants, but never far : he did not ob- 
serve that these ever rose in the air like the others c . 
From this experiment it seems as if the compound eyes 
were for horizontal sight, and the stemmata for vertical. 

The definition of them by Linne and Fabricius as 
smooth, shining, elevated or hemispheric puncta, con- 
veys a very inadequate idea of them ; for, except in a 
very few instances, they are perfectly clear and transpa- 
rent, and their appearance is precisely the same as that 
of the simple eyes of Arachnida &c, under which head 
they might very well have been arranged ; but as the last 
are primary eyes, and the stemmata secondary, it seemed 
to me best that they should stand by themselves. The 
structure of both is probably the same, and their inter- 
nal organization that of one of the lenses of a compound 
eye, and both are set in a socket of the head. 

a Bibl, Nat. i. 214. b Reaum. iv. 245. 

c Ibid. v. 287—. 



.506 EXTERNAL ANATOMY OF INSECTS. 

Though a large number of insects have them, they are 
by no means universal, since some Orders, as the Stre- 
psiptera, Dermaptera, and Aptera, are altogether without 
them. The Coleoptera, also, have been supposed to af- 
ford no instance of species furnished with them; but in the 
last number of Germar and Zincken Sommer's Magasin, 
it is affirmed that they are discoverable in Gravenhorst's 
genus Omalium, but not in the kindred genera Micro- 
peplus and Anthophagus a . Upon examining the former 
genus, I find, that although Omalium planum and affi- 
nities, O. striatulum, and some others, appear not to have 
them, yet with the aid of a good magnifier they may be 
discovered in most species of that genus ; as likewise in 
Evcesthetus Grav. I find them also very conspicuous in 
A. Caraboides and other Anthophagi, but some species 
appear to want them. In these insects they are two in 
number, situated in the vertex a little behind the eyes but 
within them, and either at each end of a transverse furrow, 
or at the posterior termination of two longitudinal ones. 
Nor are they found in all the genera of the other Orders. 
In the Orthoptera, the Blattidce, unless a white smooth 
spot on the inner and upper side of the eyes may be re- 
garded as representing them, have them not ; but in all 
the other genera of that Order they are to be found b . 
In the Hemiptera all the Cicadiadce are gifted with them ; 
as are likewise Tetyra, Pentatoma, with many other Ci- 

a Magas. der Entomolog.'ix, 410. 

b Latreille speaks of Phasma as having no stemmata; but it should 
seem that he examined only the apterous ones, all the winged indi- 
viduals, at least so far as I have examined them, having three very 
visible ones. It may, I think, be laid down as a rule, that the larvae 
and pupae of Orthoptera have not these organs. Probably their use 
is principally in flying? 



EXTERNAL ANATOMY OF INSECTS. 507 

micida, and the Reduviada very remarkably ; but many 
others in both sections of this order, as Thrips, Coccus, 
Aphis, Capsus, Miris, Naucoris, Nepa, and Notonecta, &c. 
are deprived of them a . Of the Neuroptera the Libellu- 
lina add stemmata to their large eyes, in the anterior 
angle of which they are stationed 5 ; but many other ge- 
nera of that Order are without them ; as Myrmeleon, As- 
calaphus, Hemerobius, &c. The Trichoptera and Lepi- 
doptera universally have them ; though in the latter, 
except in Castnia and the Sphingidce, they are not ea- 
sily seen. In the Hymenoptera they are usually very 
conspicuous, but in Larra and Lyrops, two genera of this 
order, the posterior pair are scarcely discernible ; and in 
the neuter ants they are quite obsolete. In the T>iptera, 
though many genera are furnished with them, yet many 
also want them ; amongst the rest Latreille's Tipularice, 
and all the horse-flies (Tabanus L.). The Pupiparte 
{Hippobosca L.) usually have none; but in Ornithomyia 
avicularia, one of that tribe, though extremely minute 
they are visible, arranged in a triangle, in the polished 
space of their vertex. 

As to the Number of the stemmata, three appears to 
be most universal. Reaumur mentions an instance in 
which he counted four in a fly with two threads at its 
tail; but great doubt rests upon this statement c . Some 
Orthopterous genera, as Gryllotalpa, and many Hemi- 



a Flata phalcenoides F. and affinities have no stemmata, while 
Flata reticulata and affinities have them : a proof that these tribes 
are distinct genera. 

b Plate VI. Fig. 10. i. 

c Reaum. iv. 243. He refers for this insect to plate xiv. without 
adding any number for the figure ; but no such is in that plate. 



503 EXTERNAL ANATOMY OF INSECTS. 

pterous, as Tetyra, Pentatoma, Reduvius*, Cercopis, 
Fulgora b , &c, have no more than two ; and in Larra 
and its affinities, as just observed, the posterior ones are 
obsolete, so as to leave only one discernible. 

Where there are three of these organs, they are usu- 
ally arranged in an obverse triangle in the space behind 
the antennae, at a greater or less distance from them. 
In those male flies (Muscidce) whose eyes are confluent, 
the stemmata are in a little area behind their conflux ; 
but, as before observed, in the drone-bee and the Libel- 
lulina they are before it. This triangle is in some cases 
nearly equilateral, as in Perla related to the may-flies, 
and many Hymenoptera ,• in others it is acutangular, as 
in Locusta &c, in which the stemma forming the vertex 
of the triangle is before the antenna c : in others, again, 
it is obtusangular, as you will see in Pepsis and vari- 
ous Hymenoptera. In the humble-bees (Bombus), a line 
drawn through them would form a slight curve. Their 
situation also varies. In insects that have only two, 
they are sometimes placed a little behind the eyes, or in 
the back part of the space between them : this is the case 
with most of the bugs {Cimex L.) that have them. — 
They are often distant, as in Tetyra F., Edessa F.; and 
sometimes approximated, as in Reduvius F. d In many 
of the Homopterous Hemiptera, as Cercopis, Ledra, &c. 
they are planted in the upper part of the head e , but in 
Iassus their situation is on the under part ; and in a North 
American subgenus, as yet without a name, they are ex- 

« Plate XXVI. Fig. 40. i. 

b Cercopis, Ibid. Fig. 42; and Fulgora, Fig. 41. i. 

c Plate VI. Fig. 4. i. 

d Plate XXVI. Fig. 40. i. c Ibid. Fig. 42. i 



EXTERNAL ANATOMY OF INSECTS. 509 

actly between the two, being placed in the frontal angle. 
In Fulgora their station is between the eyes and antennas a . 
They are most commonly sessile, and as it were set in 
the head ; but in some, as Fulgora candelaria, they stand 
on a footstalk. The stemmata are set in the side of a 
frontal tubercle in that four-winged fly of threatening 
aspect, Corydalis, which in its perfect state has mandi- 
bles, but longer and more tremendous, like those that 
distinguish the larva only of the kindred genus Hemero- 
bius b . These organs differ little in shape, being usually 
perfectly round and somewhat convex ,• but occasionally 
they vary in this respect. In Fulgora serrata they are 
oblong, with a longitudinal depression ; in F. Diadema 
they are also umbilicated, but the umbilicus is circular ; 
in Corydalis they are oval; in other insects they are 
ovate; in some semicircular, and in a few triangular. 
They vary much in size: in some of these animals being 
so minute as to be scarcely visible, while in others, as 
Corydalis, Dorylus, Vespa pallida F., Reduvius, &c. b , 
they are as large as some compound eyes. They differ 
also in colour, though often black : in Fulgora laternaria 
they are of a beautiful yellow,- in F. candelaria they are 
white; in many Hymenoptera they are crystalline, in 
others red. : the fierce look of Reduvius personatus is ren- 
dered more hateful by its stemmata having a pale iris 
round a dark pupil c . 

Let us here stop and adore the goodness of a benefi- 
cent Creator, who, though he has deprived these little 
beings of the moveable eyes with which he has gifted the 

* Plate XXVI. Fig. 41. i. 

b De Geer iii. t. xxvii./. 1. Reaum. iii. t. xxxii./. 3, 9. 

c Plate XXVI. Fig. 40. i. 



510 EXTERNAL ANATOMY OF INSECTS. 

higher animals, has made it up to them by the variety 
and complex structure of their organs of vision, where 
we have only two points of sight, giving them more than 
as many myriads. 

5. Antennae. — But of all the organs of insects, none 
appear to be of more importance to them than their An- 
tennce, and none certainly are more wonderful and more 
various in their structure, and probably uses. Upon 
this last particular I shall enlarge hereafter. Their 
structure, as far as it differs in the sexes, I fully dis- 
cussed in a former letter a ; and the most remarkable 
kinds of them will be included in a set of definitions 
which I shall draw up for you before our correspondence 
on this part of my subject closes : I shall therefore now 
confine myself to the following particulars — namely, their 
number, insertion, substance, situation, "proportion, general 
form and structure, clothing, expansion, motions, and sta- 
tion of repose.. 

As to their Number, in the majority of crust aceous ani- 
mals the antennae amount to four, but no insect has more 
than two. A genus recently established ( Otiocerus Kir- 
by b ) seems to afford an exception to this rule, since the 
species composing it at first sight appear to have four, 
and in some instances even six antennae ; but as only two 
of them terminate in a bristle, the other, though pro- 
ceeding from the same bed of membrane, may perhaps 
be regarded as merely appendages. Germar, who has de- 
scribed a species of this genus c under the name of Co- 
bax Wintheri, considers these appendages as analogous 

a See above, p. 318 — . b Linn. Trans, xin. 

L ' Mae. der Entomolos. iv. 5; 



EXTERNAL ANATOMY OF INSECTS. 511 

to palpi : but as they do not proceed from the oral or- 
gans, but from the bed of the antenna at the base of the 
nose a , they ought certainly to be regarded rather as ac- 
cessories to the latter, than as representing the former. 
In the Aptera order the mites (Acacus L.) appear to be 
without these organs. In the pupiparous tribe Hippo- 
bosca they seem about to disappear ; and in the Arach- 
nida &c, as has been more than once observed b , the 
mandibular have been thought to represent, not indeed 
the antennae of insects, but the inner pair of those of the 
Crustacea. 

In considering the insertion of antennae, by which I 
mean their articulation with the head, we must advert 
first to the orifice ( Torulus) that receives them c . This 
is a perforation of the crust of the head; commonly, 
though not invariably, circular : in Coleopterous insects 
often with concave lubricous sides, forming an acetabu- 
lum, with processes usual in ginglymous articulations, 
larger than the bulb or root of the antennae; and which is 
commonly covered, except the central space occupied by 
the bulb, with a tense membrane. Though not in gene* 
ral remarkable, in some cases it merits attention. In the 
genus Rhipicera Latr., the elegant antennae of whose 
males I have described in a former letter d , particularly 
the Brazilian species, it is a long process on each side of 
the nose, and might be mistaken for the first joint : in 
another Coleopterous genus, Priocera K. e , it has some- 
what of the shape of a trumpet : in Cupes a tubercle rises 

a Palpi quatuor, subaequales, cylindrici, ad basin clypei. Germ. 

b See above, p. 18, &c. c Plate VI. Fig. 1, 4. i'. 

d See above, p. 321. Linn. Tram. xii. t. xxi.f. 3. 

e Ibid./. 7- 



512 EXTERNAL ANATOMY OF INSECTS. 

just above the base of the antenna : a circular process 
forms the torulus in Fulgora and others. It is also often 
placed in a cavity of the front, as in several wild-bees, 
Melitta K., and in Locusta Leach on the sides of an ele- 
vation of that part a . In a large majority of insects the 
bulb {Bulbus) or ball which is received by the bed, wears 
the appearance, especially in the Hymenoptera, of a di- 
stinct joint; but if you carefully examine it, you will 
clearly see that it is merely the base of the scape swelled 
out into a spherical or other kindred form b ; and often 
marked, as in the Cicindelida, with impressed points : 
as it is the piece by which the antenna moves in its soc- 
ket, this form of a rotula was doubtless given for its more 
ready motion in all directions. This structure is princi- 
pally conspicuous in the Coleoptera and Hymenoptera 
Orders : in the others the base is not so distinguished 
from the rest of the scape. If you carefully extract the 
antennas of a beetle, say a Copris or Lamia, and examine 
its base or bottom, you will find that it is open for 
the transmission of muscles and nerves ; that in its up- 
per margin it has a deep notch or sinus, on each side of 
which is a smaller notch ; and that all round the margin, 
which is very lubricous, a membranous ligament is at- 
tached, by which it was affixed in the torulus. Its arti- 
culation, therefore, seems of a mixed kind, like that of 
most other organs and parts of insects, partaking of the 
ligamentous, ginglymous, and ball and socket. In the 



a Plate VI. Fig. 4. c. i'. 

b Plate XII. Fig. 9. 1". This circumstance was very recently 
discovered ; which will account for this plate not being quite correct 
in this respect, the bulb being represented as a distinct joint in 
Fig. 6, 10, 26. 



EXTERNAL ANATOMY OF INSECTS. 513 

Orthoptera, Flemiptera, &c. the articulation seems more 
purely ligamentous. 

With regard to their substance — these organs are re- 
gulated, in some degree, by the nature of the integu- 
ment of the animal of which they are appendages ; in the 
softer insects being of a softer substance than they are in 
hard ones. The vertex of the joints, where they receive 
the succeeding one, appears in many cases to be softer 
than the rest of it, and especially towards the apex, often 
papillose. The antennae are generally opaque ; but in 
Nebria co?npla?iata, a beetle common on the sea-coast in 
Wales and Lincolnshire, they are semitransparent. 

The situation of antennas must next be considered. 
In this i-espect it seems necessary that they should be 
so situated as to be under the direction of the eyes : for 
if you examine ten thousand insects (except, as w r as be- 
fore observed a , where there are four eyes), you will not 
find one in which these organs are situated either above 
or immediately behind them ; their station being always 
either somewhere in the space between the eyes or that 
below them. In Ptinus F. they are placed near the 
vertex; but in Gibbium, which is so nearly related to 
that destructive genus b , they are beneath them. In 
many Melittcc K. they are in the middle of the space 
between the eyes; and in many other Hymenoptera and 
Coleoptera (Staphylinus &c), in the anterior part of it. 
In many Lamellicorn genera, as Melolontha, Cetonia, 
Lucanus, &c. they may be regarded as planted in the 
lower surface of the cheek before the eyes ; but in Co- 
pris &c, in which they are inserted further under the 

a See above, p. 49S. b Vol. If p. 231, 238, 

VOL. II T. % L 



.7 14- EXTERNAL ANATOMY OF INSECTS. 

shield of the head, they are properly in the prone surface 
of the front. In the Capricorn-beetles (Cerambyx L.) and 
Cnodalon F. they may be termed inocular, or placed in 
a sinus of the eye ; in the former tribe in its interior, and 
in the latter its anterior side. In the Rhynchophorous or 
rostrum-bearing beetles (Curcidio L.) they vary in their 
situation. Thus in Macrocephalus Oliv. they are inserted 
at its apex ; in Anihribus in its middle, and in Calandra 
at its base a . In the water-scorpions (Nejoa, Belostoma, 
&c) they may be called extraocidar, being placed under 
the head in its prone part, outside the eyes b . In Nir- 
mus Fringillcc, a kind of bird-louse, they appear to be 
oral, being situated, according to De Geer, under the 
head near the mouth, at a great distance from the 
eyes c . 

In their proportions, both as to length and thickness, 
antennae vary extremely. Thus sometimes they are very 
short — much shorter than the head; as in the aquatic 
beetles Gyrinus, Parnus, and the water-scorpion; and 
some land-beetles, as Anthrenus, &c. At other times they 
far exceed the length of the insect : the males of many 
Capricorn-beetles are so distinguished. In that of Lamia 
ccdilis they are more than four times as long as the 
body ; and every intermediate length between these two 
may be found amongst them. They vary also greatly in 
thickness : in Paussus, whose antennae emit light in the 
night d , and Cerapterus, they are nearly as thick,— at 
least their knob, which forms the chief part of them, — as 

a Oliv. Ins. no. SO. Macrocephalus t. i./.l— 4.; Anthribusf. 5— \2 ; 
and no. 83. Curculio t.W. Calandra f. 16. 
b Schellenberg Cimiccs t. xiv./. 1. b. 
c De Geer vii. t. iv.f. 7- a a. J y f,. II. 0*421. 



EXTERNAL ANATOMY OT INSECTS. 51.5 

the body of the insect a ; while in Ma?itis, Acrida K. and 
Psocus, they are as slender as a hair. The antennas in 
many of the Prio?ii, especially in P. imbricornis, are thick 
from base to tip ; while in other Capricorn-beetles they 
are quite the reverse. 

It will not be necessary to enlarge here upon the ge- 
neral form of these organs : I shall therefore only notice 
the two principal divisions of them in this respect. — 
Antennas, regard being had to one of their uses, may be 
divided into two sections, distinguished by forms ex- 
tremely different: those, namely, that are employed by 
insects as factors to explore their way, and those that 
cannot be so employed. The great majority are of the 
former kind ; but those that may be denominated setige- 
rous, — as the antennas of the Libellulina, Ephemerina, of 
the Homopterous Hemiptera, and of many Diptera, the 
last joint of which terminates in a bristle, or is furnished 
with a lateral one, and of some gnats that have short 
feathered antennas, — appear not fitted to be used as tac- 
tors to explore by touch, and form the latter description. 
This difference in these organs, as I shall have occasion 
to prove more at large hereafter, furnishes a strong pre- 
sumption that their primary function is not touch. Were 
this the case, it would be common to them all. 

As to their structure, antennas consist in general of a 
number of tubular joints ; each of which having separate 
motion, the animal is thereby enabled to give them every 
flexure necessary for its purposes. The scape, or first 
joint, by means of the bulb inosculates in the torulus, or 
is suspended to it; and the others, sometimes by a simi- 

a Plates XII. Fig. 2&; and XXV. Fig. 9, 24. 
2 L 2 



516 EXTERNAL ANATOMY OF INSECTS. 

lar, though less pronounced knob at their base, inoscu- 
late in the preceding one; but in some cases the inoscu- 
lation seems not so perfect, the joints being simply sus- 
pended by ligament. In pectinated or lamellated an- 
tennae, the branch is usually a lateral process of the joint 
from which it issues ; but in Phengodes (Lampyris plu- 
mosa L.) its involute plumose branches appear to articu- 
late with the apex of each joint a . I have a specimen 
of one of the Cleridce, of a genus undescribed, in which 
each branch is forked. In some tribes of the Capricorn- 
beetles (StenoconiS) &c.) the antennas are often armed at 
their apex with spines, sometimes on the upper side and 
sometimes below. In some aquatic beetles {Gyrinus, 
Parnus) they are furnished with an auricle at their base, 
which, like the lid of a box, shuts them in when unem- 
ployed, and protects them from the water b . 

The portions into which antennas may in general be 
considered as divided, have been sufficiently explained 
to you above ; but it may not be amiss to add here a few 
words on the principal variations in their structure that 
I have had an opportunity of observing. The scapus c 
or first joint, which includes the bulbus^ is usually the 
most conspicuous joint in the antenna (exclusive, I mean, 
of the capitulum, in those in which that organ terminates 
in a knob), it being thicker and often longer than the suc- 
ceeding ones. In the Capricorn and Darkling beetles, 
indeed {Cerambyx and Tenebrio L.), the third joint is the 
longest, but the scape is still the thickest; and in the 
stag-beetles (Lucanus L.), many of the weevil tribes 

a Plate XXV. Fig. 4. 

" Plates XII. Fig. 29 ; and XXV. Fig. 28. a. 

c Plates XI. XIL XXV, k". 



EXTERNAL ANATOMY OF INSECTS. 51*7 

(Curcidio L.), and those of the bees (Apis L.), except in 
the males, it is as long nearly as the remainder of the 
antenna?, which forms an angle with it. In shape it is 
generally somewhat curved and subclavate, or increasing 
in size from the base to the summit ; but it is sometimes 
straight and filiform, at others oblong or square, at 
others again triangular, in several instances three-sided : 
in one (Cetonia cruenta F. Genuchus K.) it is, as it were, 
broken, the upper part forming nearly a right angle with 
the lower ; in Cerocoma Schafferi it is foliaceous ; and it 
is occasionally suborbicular : and probably many other 
forms might be enumerated. 

The Pedicellus* is the second, and may be deemed the 
least conspicuous joint of the antennas. Though more 
slender than the scape, it is generally thicker than that 
which immediately follows it. In broken antennae it is 
the hinge or pivot on which the clavola or upper mem- 
ber turns : it is usually very short, campanulate or bell- 
shaped, or obconical ; but in a species of bug ( Tetyra, 
from New Holland — T. pedicellata Kirb. MS.) it is 
nearly as long as all the rest of the joints taken together. 
In those species of Lycus, a genus of beetles related to 
the glow-worm, that have flattened antennas (as L. reti- 
culatus, fasciatus, &c), this joint is almost received into 
the socket of the scape, so that their antennas appear at 
first to have only ten joints, but in those which have 
those organs filiform (as L. minutus, Aurora, &c.) it is 
more conspicuous. 

The Clavola b , or remaining joints of the antennas 
taken together, constitutes the principal part of the or- 
gan, which, especially at its extremity, exercises its func- 

3 Plates XI. XII. XXV. I'. h Ibid, ra' . 



518 EXTERNAL ANATOMY OF INSECTS. 

tions of touch, or any other sense. The principal varia- 
tions, as to form and structure, that occur in this part 
will be mentioned in another place. I shall only here 
observe, that in many instances the first joint of this part 
is longer than the rest ; but in Tctyra pedicellata just 
mentioned, it is by far the shortest, and shaped like the 
pedicel of most insects. In the Libellulina, the Homo- 
pterous Hemiptera, and those flies whose antennae ter- 
minate in a bristle, the clavolet is represented by the 
bristle. But in the flies which have a lateral bristle, on 
the last joint, and those with triarticulate antennas that 
have no bristle, the terminal joint represents it. The 
clavolet often terminates in a knob, or in several joints 
thicker than that which precedes them. This varies 
greatly, not only in its form, but also in the number of 
joints of which it is composed. Thus in Paussus, Platy- 
pus, and many Calandr'ce, it consists of only a single 
joint a ; in Anthrenus, JDitoma, &c. of two ,• in Nitidula, 
Geoirupes, &c. of three b ; in Tetratoma, the Silphidte, of 
four ; of Jive in Scaphidium d ; of six in one species of 
Languria ; of seven in the common cockchafer [Melo- 
lontha vulgaris e ); of eight in Diaper is Boleti, in which 
the whole clavolet forms the club f ; of nine in Oenas ; and 
ten in Cerapterus s. All the above, you will observe, are 
beetles. In the other orders there are eleven joints in the 
knob of some butterflies ; twelve in that of Ascalaphus h 
and Myrmeleon ; and lastly, fourteen in Tracheitis '. 

• Plates XII. Fig. 28; and XXV. Fig. 13. m". 

b Plate XXV. Fig. % 5, 21. m". 

'• Plate XII. Fig. 10. m". <i Ibid. Fig. 4. m". 

c Plate XXV. Fig. 1. m". f Plate XI. Fig. 23. 

« Plate XXV. Fig. 24. n Ibid. Fig. 30. 

! Jurine Hymcnopt. t. \u.f. 3. 



EXTERNAL ANATOMY OF INSECTS. 519 

Under structure also, the number of joints of which 
antennae in general consist, should be considered. If 
you examine the insects belonging to the different or- 
ders, you will find remarkable variations in this respect. 
Let us run through them : — In the Coleoptera the na- 
tural number of joints is eleven ; but this rule is not 
without many exceptions. Thus, many have fewer than 
the prescribed number : Paussus has only two a , Clavi- 
ger and Platypus five, Dorcatoma and Calandra eight b , 
Geniates K. and Phanccus MacLeay nine c , and lastly 
Melolontha ten d . Others, again, have more than eleven 
joints : Cebrio Gigas, Chrysomela stolida, some Saperdcc, 
and several others, have twelve. In Prionus imbricornis 
the female has nineteen, and the male twenty e . Rhipi- 
cera marginata has thirty-two ; and in a New Holland 
species of this genus I counted thirty-eight. In the Or- 
ihoptera I can trace no general law in this respect. In 
Locusta Leach in some species you may count fourteen 
joints, in others sixteen, and in others twenty-five. In 
one, which appears to be a pupa, I found only thirteen. 
In Mantis they exceed thirty ; but in Blatta, from between 
thirty and forty, they reach nearly one hundred and fifty ; 
often varying in number in different individuals of the 
same species. The order Hemiptera exhibits two pecu- 
liar types of antennae, which, with some exceptions, di- 
stinguish the two natural sections into which M. Latreille 
has judiciously divided it. In the Heteropterous section 
they are without a bristle at their end ; and in the Homo- 
pterous one, with the exception of Aphis, Thrips, &c. 

* Plate XXV. Fig. 28. " Ibid. Fig. 13. 

' Ibid. Fig. 5. '' Ibid. Fig. 1. 

e Plate XI. Fig. V2. * Linn. Trans, xii. t. xxi f. 3, 



520 EXTERNAL ANATOMY OF INSECTS. 

they have one. In the genera of both these tribes, the 
number of joints varies in these organs. Thus, exclu- 
sive of the seta, in Flata and Cixius there are only ttm 
joints; in Galgulus, Fulgofa, and Cercopis, there are 
threes in Lygczus, Coreus, &c. there are four; in Tetyra, 
Penlatoma, Tettigonia, there are/foe a ; in Aleyrodes there 
are six ; in Aphis seven; in TJirips eight; in Psylla ten, 
the last of which is terminated by two bristles b ; and in 
Coccus eleven. The Neuroptera order, as it stands at 
present, is regulated by no general rule with regard to 
the number of joints in the antennas of the insects that 
compose it. Several types of form in these organs distin- 
guish its discordant tribes. The frst is that of the Ephe- 
mera, in which the antennas consist of two short joints, 
crowned by a short, tapering, unjointed bristle. The second 
is that of the Libellidina, similar to the above, but with a 
jointed bristle. The third is that of Psocus, in which the 
antenna has two short thick joints at the base, terminated 
by a long filiform bristle, consisting of seven or eight 
joints, and finer than a hair. Perhaps these three may 
be regarded as belonging to a common t}>pe. The fourth 
type is presented by the short filiform antennas of Ter- 
mes; the fifth by the setaceous ones of Corydalis, Heme- 
robius, &c; and the sixth and last by the clavate and 
capitate ones of Myrmeleon and Ascalaphus. In the 
Lepidoptera and Trichoptera orders the antennae, though 
varying in their general form in the three tribes of which 
Linne formed his genera Papilio, Sphinx, and Phalccna, 
with the exception of Hepialus, in which the joints are 

• l Latreillc says six, but only five arc discernible ; the three last 
form a kind of bristle. 
h Latr. Founnis, 323. 



EXTERNAL ANATOMY OF INSECTS. 521 

few, arc always multiarliculate : — we will therefore, with- 
out further delay, proceed to the Hymenoptera. In La- 
treille's tribe Aculeata the general rule is, that the fe- 
males shall have twelve joints and the males thirteen. 
In his IcJmeamonides the law seems to be, that the an- 
tennae shall be multiarticulate and setaceous; but in most 
of the other tribes of the order, even those that in other 
respects are most nearly related, — as in his Tenthredine- 
tce, — the number of joints of these organs varies without 
end. Thus in Hylotoma there are only three joints a ; 
in Cimbex lceta h Jive; in C. axillaris and Perga Leach c , 
six : and so on to twenty-five or more d . The same fluc- 
tuation in this respect runs throughout , the rest of the 
order. In the Diptera there are two general types of 
antennas : — those of the Tipularia Latr., consisting usu- 
ally of from fourteen to sixteen joints, in the males often 
resembling beautiful plumes ; and those of the remainder 
of the order, in which they do not exceed three joints e : 
though the last, or patella, is often further divided into 
obsolete or indistinct ones f . These antennas may be 
farther subdivided into Jilatce and aristatce, or those 
without and those with a bristle, either lateral or ter- 
minal. 

The clothing of antennas also merits attention, since it 
is often not a little remarkable. By clothing I under- 
stand the down or hairs of every kind with which they 
are either generally or partially covered. A great number 
of filiform aud setaceous antennas of Predaceous beetles 
(Cicindela L., Carabus L.) have the first two, three, or 

" Jurine Hymenopt. t. vi.f. 3. b Ibid.f. 2. 

-• Ibid.f. 1 . Plate XXV. Fig. 7- d Plate XXV. Fig. 25, 26. 

« Plate XII. Fig. 16—22. ' lbkl Fig. 19. a. 



5'2'2 EXTERNAL ANATOMY OF INSECTS. 

four joints naked, and the rest covered with a fine down. 
In insects that have a knob at the end of these organs, 
whether lamellated or perfoliate, this down is often con- 
fined to it, or to its intermediate joints, and seems inter- 
mixed with nervous papilla?. These are particularly vi- 
sible in the flabellate antennas of Rhipicera, Lampryris 
Lalreillii a , Elaterjlabellicornis b , &c. covering both sur- 
faces of the processes of the joints. In some male bees 
these papilla? are inclosed in hexagonal spaces into which 
the antenna? are marked out c . It is to be observed, 
that in many antenna? the joints of the clavolet have one 
or two bristles or more at their apex, one above per- 
haps, and one below; the lower angle in those of the 
serrated antenna? of Elater is usually so furnished, and 
sometimes the upper. In many Capricorn-beetles and 
various insects the antenna? are clothed, instead of down, 
with stiffish hairs or short bristles. Other insects have 
these organs, at least the clavolet, beset with longer hairs 
standing out from them on all sides: of this kind are 
those of a singular beetle (Sarrotrium muticum) some- 
times found in this country d . Again, there are some 
that have only their underside bearded with longer hairs; 
as Lamia curculiouoid.es, speculifera K., and other Ca- 
pricorns e . In another of this tribe, Saperda hirsuticoi- 
nis, the three intermediate joints are ornamented with 
branches of long black hairs, which give them an elegant 
and feathery appearance f . In Callichroma alpina the 

3 Linn. Trans, xii. I. xxi.f. 3, 4. Plate XXV. Fig. II. 

b Plate XI. Fig, 17. 

'■ Kirby Mon. Ap. Angl. i, 184. t. x. «.*. d. 1. f. 8. 

" Plate XXV. Fig. 27- c Plate XII. Fig. 26. 

f Plate XXV. Fig. 32. 



EXTERNAL ANATOM>* OF INSECTS. 523 

apex of the slate-coloured joints of its antennae is bearded 
with black hairs. In Lamia reticulata, and Saperda 
fasciculata and plumigera, all also Capricorns, a single 
bunch of hairs, resembling the brush of a bottle-cleaner, 
signalizes the middle of the antenna a : in Saperda sco- 
pulicornis K. this is star-shaped b . Sometimes the scape 
is externally bearded, as in Trar, a beetle found in horns 
and bones ; and in many other Lamellicorns c . In this 
last tribe the two exterior leaves of the knob of the an- 
tennae are often set with short bristles d ; and in a minute 
beetle called by De Geer Dermestcs atomarius, the hairs 
of this part are said to form a brush e . 

When insects, I mean more particularly Coleoptera, 
are about to move from any station where they have 
been at rest, the first thing they usually do, before they 
set a step, is to bring forward and expand their antennae, 
which have either been carefully laid up in a cavity fitted 
to receive them, or back upon the body: if they termi- 
nate in a lamellated knob, they separate the lamellae as 
far as possible from each other; or if it is perfoliate, the 
joints of it mutually recede. The object of this is evi- 
dently to collect notices from the atmosphere, since the 
papillose part of these joints cannot be applied to sur- 
faces. When the animal begins to move, in many cases 
the antennae do the same, and continue their motion till 
it stops and returns to a state of repose. In the parasitic 
tribes of the Hymenoptera {Ichneumon L.) they are kept 
in an almost constant vibration. Many other insects 
move them in all directions without any order or regu- 

a Plate XII. Fig. 25. b Plate XXV. Fig. 17. 

c Linn. Trans, xii. /. xxiii.f. h.f. '' Ibid, tTxxi. f. 8 g. 9, 10. e. 

p De Gecr iv, 219. /. viii./. 20. 



52 1< EXTERNAL ANATOMY OF INSECTS. 

larky.; and others when they elevate one depress the 
other, and so proceed as if balancing themselves by 
means of these organs like a rope-dancer. I have before 
stated to you how by motions of their antennae, ants and 
bees communicate their wants or discoveries to each 
other, or make inquiry concerning any thing they wish 
to know a . But as I shall have occasion to make some 
further remarks upon this subject, when the senses of 
insects are under discussion, I shall for the present take 
my leave of it. 

I shall conclude what I have to communicate to you 
relative to the organs of which we are treating, with a 
few observations with respect to their station when the 
insect reposes. In the Capricorn-beetles, Encera and 
other insects with long antenna?, they are merely turned 
back or on one side with no particular cavity for their re- 
ception when unemployed, but probably the apex passes 
under the body. In the Predaceous and Darkling bee- 
tles (CarabusI^. Tencbrio L.) their station is usually un- 
der the sides of the prothorax, and in the Tortoise bee- 
tles (Cassida), under its anterior margin. In the Elastic 
beetles (Elate)-) they are received into a groove between 
the under margin of that part and the fore-breast (antc- 
pccius). In Anthrenns, when the animal reposes or 
counterfeits death, the antennas are concealed in a ca- 
vity of the underside of the prothorax, at right angles 
with the throat b . In the kindred genus Byrrhus^ another 
simulator of death, a large cavity is excavated under the 
same part, to receive both the forelegs and antennas, a 
narrow space being left between the angle of the pro- 

a Sec Vol. II. p, 65, 20 l-™« » De Gecr iv. t. vii./. 22. 



EXTERNAL ANATOMY OF INSECTS. 525 

thorax and fore-breast exactly admitting the base of the 
latter, which are quite concealed under the former. In 
Cryptocephalus and Chlamys, kindred beetles, when at 
rest they are withdrawn, except their scape and pedicel, 
with the head within the cavity of the protJiorax. I n 
others they are turned under the head, without any par- 
ticular cavity for their reception; as in many moths, 
Apion, &c. In most of the Lamellicorn beetles their sta- 
tion is in the cavity formed by the eye and the throat, 
the knob forming, an angle with the rest of the antenna. 
In Heterocerus they follow the contour of the eye a . In 
BrentuSf a genus of weevils remarkably long and slen- 
der, they are turned back and received by a slight longi- 
tudinal cavity of the rostrum ; but in those of this tribe 
{Curculia L.) in which the clavolet forms an angle with 
the long scape, this latter part, bending back, is laid up 
in an oblique channel of that part; and the former, 
pointing in the contrary direction, is folded upon it. In 
many flies {Muscidcc) a vertical frontal cavity receives 
the antennas, which point downwards during repose b . 
Cryptocerus, a very remarkable ant, has on its head a 
sino-ular square plate, the sides of which form a deep 
longitudinal cavity: in this cavity the antenna?, quite 
concealed, repose in safety. A cavity equally remark- 
able is exhibited by the water-scorpions, particularly 
Belostoma, in which is a very deep kidney-shaped box, 
between the eye, and throat, to receive and defend its 
singular antenna? c ; which, when they are reposing, is 
closed by the exterior harder joints, and from which it 
seems as if they turned out, like a sentinel out of his box. 

a Plate XXV. Fig! 35. h De Gcer vi. t. If. 5. 

c Plate XI. Fig. 21. 



526 EXTERNAL ANATOMY OF INSECTS. 

In some aquatic genera of beetles, as Gyrinus, Parnus, 
&c. they are withdrawn within a lateral cavity of the 
same part, and are defended from the water externally 
by the auricle at their base a . The flabellated and la- 
mellated antennae, previous to their being folded for re- 
pose, close all their plates; which in action are as widely 
expanded as possible, so as to form a knob; and in some 
the middle piece is entirely concealed, as if in a box. 
In broken antennas, or those in which the clavolet forms 
an angle with the scape, the former is folded upon the 
latter, with its point downwards. 

II. Subfacies. — Having dispatched the Fades, or up- 
per side of the head, I am next to consider the Sub- 
facies, or under side : but as the principal parts that oc- 
cupy this side have been already considered, I shall have 
no occasion to detain you long. 

i. Jugidum b . — This part, which may be regarded as 
analogous to the throat in vertebrate animals, lies between 
the cheeks ; from which it may usually be distinguished 
by being more lubricous and tumid, and often separated 
by an impressed line. It is particularly conspicuous and 
elevated in the Lamellicorn beetles, and calculated by its 
lubricity for easy motion in the lower side of the cavity 
of the chest. Its apex is the base in which the mentum 
sits. It is not necessary to enlarge further upon it, as it 
seldom exhibits striking characters. 

III. Collum c . — In a large proportion of insects the 
head inosculates in the trunk without the intervention 

a Plate XII. Fig. 29. a. "> Plate VI. m. « Ibid. 



EXTERNAL ANATOMY OF INSECTS. 527 

of a neckj or a constriction of the head behind. In the 
Orders Orthoptera, Trickoptera, Lepidoptera, Hymeno- 
ptera, and Diptera, no instance of it that I recollect oc- 
curs : in the Coleoptera there are many. In the Preda- 
ceous beetles, though several have no distinct neck, yet 
others, as Anthia, &c. have a short and thick one ; and 
some few, as Colliuris, Agra, &c. one more pronounced. 
Latreille has named a tribe in this Order Trachelides, 
from the circumstance of their having; a neck: in this 
tribe you will find the blister-beetles (Cantharis and My- 
labris) both of the moderns and the ancients. In the 
Hemiptera order the water-scorpions Nepa, &c. have a 
thick short neck; and Zelus, (a kind of bug,) one longer 
and more slender ; and, like Raphidza, the snake's-head 
fly, which is similarly circumstanced, has the air of a 
serpent. Other Neuroptera, likewise, have a neck; as 
Hemerobius, Corydalis, &c. This part presents no other 
features that merit notice. 

IV. MyoglypJiides a . — The Myoglypkides, or muscle- 
notches, are sinuses, some shallow and some deeper, in 
the posterior margin of the upper side of the head, to 
which the levator muscles are affixed. They seem prin- 
cipally confined to the Coleoptera; though, in some 
cases at least, they may be traced in the Heteropterous 
Hemiptera. These notches vary in number and depth 
in different insects. Thus in Buprestis there is only one 
deep one b : in Copris there are two shallow ones, in a 
deep sinus separated by a small prominence c : in Elater 
and Lamia there are also two not in a sinus ; and in Ca- 

• Plate XXVH. Fig. 1, 3—5. n'. " Ibid. Fig. 3. 

c Ibid. Fig. 4. 



528 EXTERNAL ANATOMY OF INSECTS. 

landra Palmarum there are four, two on each side, with 
a prominent lobe between them a . To each of these 
notches, at its under margin, below the ligament that 
unites the occiput to the trunk, a muscle to raise the 
head is usually attached. 

a Plate XXVII. Fig. 1. 



LETTER XXXV. 



EXTERNAL ANATOMY OF INSECTS, 

CONTINUED. 
THE TRUNK, AND ITS PARTS AND ORGANS. 

x\.S the head of insects is the principal seat of the organs 
of sensation, so is the trunk of those of motion ; and in it 
are contained the muscles by which they are moved : it 
may therefore be regarded as the great centre of motion, 
and as the main support and prop of the two other pri- 
mary sections of the body — the head and abdomen, be- 
tween which it is situated — it may be deemed the most 
important part of the insect, the key-stone of the whole 
structure. In treating upon it, for the greater clearness, 
I shall consider its substance, general form, proportions, 
composition, internal processes, and members. It will first, 
however, be necessary to assign my reasons for the no- 
menclature of its parts that I have adopted. 

Had the entomological world been universally agreed 
upon this subject, and there was an established system 
of Orismology a , I should have proposed no alteration 
without great reluctance, and the fullest conviction of the 
absolute necessity of some change ; but as the standard 

a For the reason which induced the authors to use this word in- 
stead of Terminology, before employed, see Vol. I. Pre/, p. xii — . 
They are gratified to see that M. Latreille has adopted this term in 
the work quoted on the other side, p. 194. 

VOL. III. 2 M 



530 EXTERNAL ANATOMY OF INSECTS. 

of language in our science is still unsettled, and different 
terms are used by different writers, there seems full li- 
berty left to me to select those that appear upon the 
whole most appropriate ; and where proper and signifi- 
cant terms seem wanting, to invent new ones. M. La- 
treille, in a late Essay a , has proposed many changes of 
this kind, and seems to hesitate concerning the adoption 
of some of those recently coined in France for the parts 
of the trunk b ; it may therefore, I think, be permitted 
me to labour a litde in this hitherto imperfectly cultured 
field, and to suggest such improvements as the subject 
may seem to require or admit. 

Linne called the part we are now considering the 
trunk, its upper-side he usually denominated the thorax, 
and its under-side the breast : he notices also the scutel- 
lum and sternum c . As the prothorax and scutellum are 
the only apparent parts of the back of the trunk in his 
first Orders (Coleoptera, Hemiptera L.), the rest being 
covered, in noticing these he puts the part for the whole, 
calling the prothorax the thorax, but which strictly was 
not synonymous with what he called by the same name 
in the other Orders. Linne's phraseology with regard to 
the trunk of insects was adopted by Fabricius and other 
Entomologists, till Illiger employed the term thorax to 
designate the whole of the trunk d , calling the upper part 
thorax superior and the lower thorax inferior. M. De 
Blainville, M. Latreille, and other French writers, im- 

;i Organisation Extericure des Insectcs, Mem. du Mus. t. viii. 

b Ibid. 199 — . I have never been able to procure M. Audoin's 
Memoire on this subject. 

Fundament.. Entomolog. in Amcen. Acad. vii. 143. 

•' Terminologie, 1578, Ike. He afterwards called the trunk Strt/ii- 
dium: Terminologie dev In&ekten, Magaz. 180G. 14. 



EXTERNAL ANATOMY OF INSECTS. 531 

proved upon this, naming the upper part the back (dor- 
sum), and the lower the breast (pectus); and dividing the 
trunk, or according to them thorax, into three sections, 
each bearing a pair of legs. But I see no sufficient reason 
for this alteration — the terms trunk, thorax, and breast, 
in the common acceptation are well understood, and lead 
to no confusion or glaring impropriety ; I shall therefore 
adhere to the old phraseology, especially as French En- 
tomologists in popular language still do the same. 

As to the division of the trunk into segments by M. La- 
treille and others, it has been regarded as consisting of 
three primary ones, which have been called in the order 
of their occurrence, reckoning from the head — prothorax, 
mesothorax, metathorax. The first of these segments, 
however — and the learned Entomologist just named seems 
to hint as much a — is usually more distinct from the other 
two, than they are from each other. If this idea be cor- 
rect, the trunk is properly resolvable into two pi'imary 
segments, the first bearing the arms or fore-legs, and the 
other the proper legs and the organs of flight. M. Cha- 
brier calls the latter tronc alifere, or wing-trunk; — a 
happy term, which I have adopted and latinized, call- 
ing it the alitrunk (alitrmicus) : the first segment, because 
it bears the fore-legs, I have named manitrunk (mani- 
truncus). I adopt likewise the terms above mentioned, 
prothorax, mesothorax, metathorax, to signify the three 
segments into which the thorax of Linne, or the upper 
side of the trunk, is resolvable; and those of the breast 
I denominate antepectus, medipectus, and postpectus. If 
terms be thought necessary to designate the two intire 

a Organisation, #r, 198. 
2 M 2 



532 EXTERNAL ANATOMY OF INSERTS. 

segments into which the alitrunk is resolvable, the first 
mav be the meditrunk {meditruncus), and the other the 
potrunk (potruncus). 

I. Substance. — With regard to its substance, the trunk 
in general is softer than the head, and harder than the 
abdomen, especially as to its upper surface ; but in some 
cases, where it is not protected by the elytra, as in the 
rove- beetles {Staphylinus L.), the abdomen appears as 
hard as the trunk. Though usually not very different 
from the elytra in this respect, in Meloe, Lytta, and other 
vesicatory beetles, it is of a firmer consistence. 

II. General Form. — In the Coleoptera Order the only 
part of the trunk that is visible on its upper-side is the 
prothorax : the mesothorax, with the exception of the scu- 
tellwn, and the metathorax, being entirely concealed by 
it and the elytra; so that, with regard to shape, it may 
nearly be considered as merging in the prothorax. Be- 
low it is more visible, and may be slated as more or less 
quadrangular; in oblong beetles inclining to a parallel- 
ogram, and in shorter or hemispherical ones to a square. 
In the majority it is more convex below than above, except 
in the case of the hemispherical or gibbous beetles (Coc- 
cinella, Erotylus, &c), in which the under-side is flat and 
the upper-side very convex. In the Diurnal Lepido- 
ptera the trunk approaches to a cubical shape, in the 
Nocturnal it is more spherical. A similar difference ob- 
tains in the Hymenoptera and Diptera : in the bees, 
wasps and flies, the trunk approaching to the figure of 
a sphere; in the ants, Scolice, crane-flies, &c. to that of 
a cube. The upper part of it in many Ichneumonida, 



EXTERNAL ANATOMY OF INSECTS. 533 

female ants, &c. is very elevated, forming an arch, and 
sloping towards the abdomen. In general it may be ob- 
served with respect to the remaining Orders, that the 
form of the trunk merges in that of the whole body, the 
tendency of which is often to a three-sided figure. 

III. Proportions. — The trunk is usually longer and 
larger than the head and longer than the abdomen, but 
not wider : but there are exceptions to both these rules. 
In Colliicris, Mantis, &c, it is more slender ; and in Atta 
megacephala and some neuter ants, it is shorter than the 
head ; in Atractocerus, many Staphylinidce, Phasma, the 
Libelhdhia, the Lepidoptera, and various Hymenoptera, 
it is shorter, and in the Mantidce more slender than the 
abdomen. The greatest disproportion between it and the 
last part is exhibited by the genus Evania, parasitic 
upon the Blattce, in which the abdomen appears merely 
as a minute and insignificant appendage of the trunk. 
The vertical diameter of this part, almost without ex- 
ception, is greater than that of either head or abdomen. 
When we consider that it contains the muscles that move 
both the organs of flight and the legs, we see clearly the 
reason why the Creator gave it greater volume. 

IV. Composition. — I lately intimated to you that the 
trunk, though resolvable into three segments, in most 
cases properly consists of only two primary ones. Who- 
ever examines the perfect insects of every Order, except 
the Aptera a , will find this distinction strongly pointed 

- 1 In Nirmus Anseris, &c. however, in this Order, the same distinc- 
tion is observable. 



531< EXTERNAL ANATOMY OF INJECTS. 

out, not only by the different direction of the first pair of 
legs from that of the two last, but also in a large pro- 
portion by a deep incisure ; and in all it is further mani- 
fested by the anterior segment having a motion distinct 
from that of the rest of the trunk, and separating readily 
from it; and this not only where it is large, as in insects 
that have a thoracic shield, but also in those in which 
the prothorax is less apparent : whereas the other two 
pedigerous segments have little or no distinct motion, 
will not readily separate from each other, and in some 
cases exhibit no pectoral suture between them. Some- 
times, however, these two last segments are more promi- 
nently distinguished : in Lytta, Mylabris, and other ve- 
sicatory beetles, they are separated below by an incisure, 
or rather the first or mid-leg segment, is not nearjy so 
elevated as that of the hind-legs. In some ants (Atta 
Latr.), in the neuters, there is no distinction of segments 
in the trunk; but in others (Formica Latr.) it follows the 
general law, and consists of three. In the Arachnida, 
with the exception of Galeodes, in which the head is di- 
stinct, and the three segments of the trunk may be traced, 
these parts together form only a single segment. In- 
duced by these reasons, I consider the trunk as consist- 
ing in general of two primary segments, the manitrunJc 
and alitrunk : the latter resolvable into two secondary 
ones. 

* Manitruncus a . — The manitrunk, then, is the ante- 
rior section of the trunk, which bears the arms and con- 
tains the muscles that move them. This part has free 
motion, or a motion independent of that of the rest of the 

» Plates VIII. & IX. a. 



EXTERNAL ANATOMY OF INSECTS. 535 

trunk. This indeed seems a necessary result of the di- 
rection and uses of the arms. It consists of an upper 
and lower part — the prothorax and antepectus. 

i. Prothorax a . — The upper part of the manitrunk in 
the Coleoptera, Orthoptera, and Hemiptera, is by far the 
most conspicuous part of the trunk, but in the other Or- 
ders it is less so. With respect to it, insects may be di- 
vided into two classes — those that have and those that 
have not & prothorax. In the Coleoptera Order it is re- 
markable both for size and variations in its shape and 
sculpture. In the Orthoptera, though less various, it 
is almost equally conspicuous, especially in Blatta. In 
the Hdmopterous section of the Hemiptera, in many ge- 
nera it has become extremely short ; while in the Hete- 
ropterous section its dimensions are not much reduced. 
In the majority of the Neuroptera, likewise, it is compa- 
ratively large ; in the Libellulina much shorter, and in 
the Trichoptera and Lepidoptera nearly evanescent b . — 
In the Hymenoptera and Diptera, with very few excep- 
tions, the thoracic shield altogether disappears, at least 
if I am correct in an idea, which I shall hereafter explain, 
that the collar usually regarded as the analogue of the 
prothorax, is really a part of the alitrunk. In these last 
Orders, though there is no true prothorax, the mani- 
trunk still remains under the form of an antepectus, 
bearing the fore-legs, and containing the muscles that 
move them. 

The prothorax of insects may in general be considered 

a Plate VIII. a. 

h If the head of any individual of these two Orders be carefully 
taken off', it will be found that above there is a very short piece repre- 
senting the prothorax, and quite unlike the collar of Hymenojifcra. 



536 EXTERNAL ANATOMY OF INSECTS. 

with respect to its parts, margin, appendages, shape, 
sculpture, clothing, and proportions. 

1. The prothorax, regarded as a whole, distinct from 
the antepectus or fore-breast, consists commonly of two 
pieces — the shield, or upper part % and the ora, or under 
part b . In the shield you are to observe its apex c , base d , 
sides % limb*, and disk*. The apex is the part next the 
head ; the base that next the abdomen; the limb the cir- 
cumference, and the disk the central part. In many Or- 
thoptera and Heteropterous Hemiptera, the shield ap- 
pears further to consist of two pieces, an anterior and 
posterior one. The ora is a continuation of the shield 
below the lateral margin, turned downwards and in- 
wards towards the fore-breast and the legs, but separated 
from the former in most cases by a suture, as in Cara- 
bus L. ; and in others merely by an impressed line, as in 
Blaps F. ; but in Curculio and Cerambyx L., &c. there is 
no ora, the shield being without a lateral margin, and 
forming one piece with the antepectus. The part we are 
now considering varies in different genera. Sometimes 
it is very narrow, as in Scarites ,• at others very broad, as 
in Buprestis, Nepa, &c. In Lampyris, except L. italica, 
and affinities, it projects posteriorly into a lobe or tooth, 
which forms a right angle with the rest of the ora, and 
becomes the lower part of the cavity that receives the 
head ; and in JDermestes this part is excavated into an 
anterior and posterior one which admits the antennas and 
arms when folded for repose. 

2. The margin of the prothorax is a ridge, either de- 

* Plate VIII. Fig. 1. * Ibid. Fig. 2. a. 

Ibid. Fig. 1, 10. a. «i Ibid. b. 

e Ibid. c. f Ibid. b. s Ibid, a, 



EXTERNAL ANATOMY OF INSECTS. 337 

fining its sides or whole circumference. In many cases 
this margin is broad and dilated, but in others it is merely 
a thread or bead that separates the shield from the ora. 
Though generally terminating the upper surface, it some- 
times, as in Staphylinus, dips below it. In many insects, 
however, as I just observed, the thoracic shield has no 
lateral margin whatever. 

3. Various and singular are the appendages with which 
the prothorax of numerous insects is furnished. Many of 
these are sexual distinctions, and have been before de- 
scribed to you a ; but there are others common to both 
sexes, the most remarkable of which I shall notice. — 
Some are distinguished by a long horn which overhangs 
the head, as Membracis cultrata, ensata, &c. b ; in others 
it stands upright, as in Centrotus spinosus c ; C. Tau- 
rus has a pair of thoracic horns like those of a bull, 
only dorsal d ; in Ledra aurita they are flat, and repre- 
sent ears e ; in some species of Tingis ( T. Echii, Pyri, &c.) 
a kind of reticulated hood, resembling lace, is elevated 
from the anterior part of the prothorax, which receives 
and shelters the head f . In Centrotus globularis and cla- 
vatus F., especially the former, thepartin question is armed 
by a most singular and wonderful apparatus of balls and 
spines, — in one case standing erect s , and in the other be- 
ing horizontal h , — which gives these animals a most extra- 
ordinary appearance. In many of the species here quoted 



a See above, p. 327— • 

b Coquebert Illustr. Ic ii. t. xviii./. 2, 4. 

<■ Stoll Cigales t. xxlf. 116. d Ibid. t. xi./. 53. 

e Plate II. Fig. 4. " f Plate XIII. Fig. 18. 

3 Stoll -Cigales t. xxviii./. 163. 

h Ibid. t. xxi.f. 115. Coquebert Must. Ic. ii. t. xviii./, 5. 



538 EXTERNAL ANATOMY OF INSECTS. 

the prothorax is producted posteriorly into a long scu- 
telliform horizontal horn, which more or less covers the 
wings and abdomen ; a circumstance which also distin- 
guishes the genus Acrydium F. (Tetrix Latr.). This 
horn seems to have been sometimes regarded by Linne 
and Fabricius as a real scutellum, and sometimes only as 
a process of the prothorax : but that it is merely the 
latter will be evident to you, if you examine carefully 
any insect furnished with this appendage ; for if you re- 
move that part, you will discover the true scutellum and 
other parts of the trunk concealed beneath it. A very re- 
markable prothoracic appendage is exhibited by some 
species of Mantis. In general the part we are treating 
of in this tribe is very slender ; but in M. strumaria, gon- 
gyloides, &c, it appears dilated to a vast width, and as- 
sumes, either partially or generally, a subrhomboidal 
form ; but if it is more closely examined, it will be found 
that the form of the prothorax is really similar to that of 
the rest of the tribe, but that this part is furnished on 
each side, either on its whole length or anteriorly, with a 
large membranous flat subtriangular appendage resem- 
bling parchment 5 . Perhaps this kind of sail may be useful 
to the animal in flight. In Prionus coriarhis &c. its sides 
are armed with teeth, and in many Lamia, Cera?nbyces, and 
other Capricorn beetles, and often in various bugs (Pen- 
tatoma Latr.) with sharp fixed spines. But the protho- 
rax has moveable as well as fixed appendages ; of this 
kind are those spines (umbones), whose base is a spheri- 
cal boss moving in an acetabidum of the thoracic shield 
of the Capricorn subgenus Macropus Thunb. If I might 

* Stoll Spectres t. si./. 43. t. xii./. 45. t. xvi./. 58, 59. 






EXTERNAL ANATOMY OF INSECTS. 539 

hazard a conjecture, I should say that these organs were 
given to this animal by an all-provident Creator, to en- 
able it to push itself forward, when in the heart of some 
tree it emerges from the pupa, that it may escape from 
its confinement. Another kind of moveable appendages 
are attached to the thorax of Lepidoptera, usually in the 
form of a pair of concavo-convex scales covered exter- 
nally with a tuft of hairs a . M. Chabrier, who examined 
these scales in recent insects, describes them as vesicles, 
which appeared to him full of a liquid and of air, and ca- 
pable of being alternately inflated and rendered flaccid ; 
he regards them as accessories to a pair of spiracles, 
which he looks upon as vocal b , opening into the mani- 
trunk just above the insertion of the arms. These or- 
gans are quite distinct from the tegulce that cover the 
base of the primary wings of insects of this Order c , and 
are what, borrowing a term from Mouffet d , I have called 
in the table patagia, or tippets. Under this head I may 
include the caruncles at the anterior angles of the pro- 
thorax of a genus of beetles with soft elytra, named by 
Fabricius Malachius. When pressed, says De Geer 
of these insects, a red inflated soft vesicle, of an irregu- 
lar shape, and consisting of three lobes, emerges from 
the thorax and from each side of the anterior part of the 
abdomen, which re-enters the body when the pressure is 
removed e . M. Latreille seems to think that these vesi- 
cles have some analogy with the poisers of Diptera and 

1 Plate IX. Fig. 4. 

b Sur le Vol des Ins. c. vii. 374. t. xviii./. 9. i i. 

<■ Plate IX. Fig. 5. d Theatr. Ins. 98. 

,: De Geer iv. 74. 



510 EXTERNAL ANATOMY OF INSECTS. 

the pectens of scorpions ; and that they are connected 
with the respiration a . 

4. We are next to say something upon the shape of 
the jprothorax. The forms of the thoracic shield, espe- 
cially in the Coleoptera, are so various, that it would be 
endless to aim at particularizing all ; but it may be use- 
ful to notice a few of the most remarkable. The pro- 
thorax of Moluris, a darkling-beetle, approaches the 
nearest of that of any insect to a spherical form, from its 
remarkable convexity ; in the wheel-bug (Reduvius ser- 
ratus) it is compressed, and longitudinally elevated into 
a semicircular serrated crest : it is crested, also, in many 
Locustce and Acridce, in some having two parallel ridges; 
but, generally speaking, its surface is more depressed. 
In Necrodes it is nearly circular, in Blatta petiveriana 
semicircular, in Nilion and some CoccinellidcE crescent- 
shaped, in Carabus obcordate, in Cantharis and Sagra 
approaching to a square, in Languria to a parallelogram ; 
in many Cimicidce, Belosto?na, &c, it is triangular, with 
the vertex truncated; it is trapezoidal in Elater, in Ateu- 
chus rather pentagonal, and exhibiting an approach to 
six angles in some other beetles b : but the prothorax 
most singular in form is that of some species of M. La- 
treille's genus Helceus c , as H. perforatus, Brownii, &c. : 
in these its anterior angles are producted, and curving 
inwards, lap at the end one over the other, so as to form 
a circular orifice for the head, which otherwise would be 

a Organisation Exterieure des Ins. 177- 

h A subgenus, related to Lebia (Hexagonia K. MS.) and some Ci- 
micidce, are so circumstanced. 
c Regne Animal in. t. xiii.y*. 6. 



EXTERNAL ANATOMY OF INSECTS. 541 

quite covered by the shield. Thus the upper portion of 
the eyes can see objects above, as well as their lower por- 
tion those below. I might enumerate many other forms, 
but these are sufficient to give you some notion of the 
variations of this part. 

5. The prothorax is equally various in its sculpture ,- 
but since in the Orismological table almost every instance 
of it has its place, I shall here only notice it as far as it 
is common to the whole tribes, genera, or subgenera. 
The Scarabceidce of Mr. W. S. MacLeay are distin- 
guished by a small excavation on each side of this part, 
which, as has been before remarked a , furnishes an ele- 
vated base for an internal process with which the ante- 
rior coxce ginglymate. In Onitis and Phanceus, to these 
excavations are superadded a pair impressed in the base 
of the prothorax, just above the scutellum ; in Carabus L. 
a longitudinal channel divides the thoracic shield into 
two equal portions ; and many genera of that great tribe 
have in addition, at the base on each side, one or two 
excavations or short furrows. Elophorus F. has on this 
part several longitudinal channels, alternately straight 
and undulated. Generally speaking, in Carabus L. the 
prothorax has no impressed points ; but in one or two sub- 
genera of Harpalidce (Chlcenia &c.) it is thickly covered 
with them. In numbers of Locusta Leach, the part we 
are considering is what Linne terms cruciate, being di- 
vided into four longitudinal portions by three elevated 
lines, the intermediate one being straight, and the late- 
ral ones diverging from it both at their base and apex, so 
as to form a sinus or angle b . In certain Acridce K. 

a Sea above, p. ."98. b Pt.ate XIII. Fig. 17. 



542 EXTERNAL ANATOMY OF INSECTS. 

{Locusta F.) there are only two of these lines or ridges, 
but notched or toothed ; and in some of the genus first 
named only one a ; in Locusta Dux and affinities the^ro- 
thorax has several transverse channels or rather folds b , 
with corresponding ridges on its internal surface. 

6. With respect to the clothing of the prothorax, I have 
not much to say : in Coleopterous insects this part is com- 
monly naked; but in some genera, as Byrrhus, Anthrenus, 
Dermestes, and many weevils [Curculio L.) it is partially 
or totally covered with hairs or scales. In the other tho- 
racic Orders it is usually naked, but in some Neuroptera, 
the Myrmeleonina, &c, it is hairy; and in the Libellulina 
it is fringed posteriorly with hairs. 

7. As to its relative proportions^ the prothorax is some- 
times rather wider than the rest of the trunk and the 
head, as in Onitis, Pasimachtis, &c; it is considerably nar- 
rower in Collyuris and Odacantka; and of the same width 
in those Scaritidce with striated elytra c . Again, it is 
sometimes of the same width with the elytra, but wider 
than the head, as in Hydrophilus, Dytiscus, &c. ; in some 
instances it is of the same width with the head, and nar- 
rower than the elytra, for instance in Anthia and Bra- 
chinus. In most Coleoptera it is longer than the head 
and shorter than the elytra ; but in Manticora, the vesi- 
catory beetles, &c, it is shorter than either. In Gnoma 
lo?igicollis d , it is nearly as long as the elytra; in many 
Staphylinidce, Atractocerus, &c, longer ; in Phanceus car- 
nifex, bellicosus, &c, it is longer than the elytra and the 
rest of the body. With regard to itself, it is sometimes 

a Plate VIII. Fig. 10. b ibid. 

e Linn. Trans, vi. t, xxi./. 10, d Ihki. f. 8. 



EXTERNAL ANATOMY OF INSECTS. 543 

very wide in proportion to its length — Dytiscus, Helceus j 
at others very long in proportion to its width — Colliuris, 
Brentus, Mantis, &c. In Plata, and many other Ho- 
mopterous Hemiptera, it is extremely short ; extremely 
long in Glioma; in Sagra and Donacia its width about 
equals its length ; in Plater, Dytiscus, and many Hete- 
ropterous Hemiptera, it is narrowest before ; in Langu- 
ria it is every where of equal width ; in Anthia, Carabus, 
&c., it is widest before ; and, lastly, in the Scarabceidce 
MacLeay it is usually widest in the middle. 

ii. Antepectus a . — The antepectus, as was before ob- 
served 5 , in some tribes forms one piece, without any 
kind of separation, with the prothorax ,• but very often 
this is not the case. In Carabus L. it occupies almost 
the whole under-side of the manitrunk ; but in Plater, 
in which the or a is very wide, the antepectus is merely 
the middle portion of that part. In Carabus F. &c. be- 
tween the ora and the base of the arms is a convex tri- 
angular piece, distinguished from the rest of the ante- 
pectus by a spurious suture ; and in Pentatoma and other 
Heteropterous Hemiptera a similar piece is observable, 
which terminates in a convex bilobed subtriangular 
sheath, receiving the base of the clavicle c . This piece 
seems a prop to that part, and analogous to the scapula 
of the medipectus and parapleura of the postpectus. I 
shall say no more upon the antepectus, as it is seldom 
remarkable. In the mole-cricket, however, one peculia- 
rity distinguishes it: it is in this of an elastic leathery 

« Plate VIII. b. " See above, p. 536. 

c Something of the kind is observable at the base of the other 
legs in this tribe. 



Jj44 external anatomy of insects. 

substance, while the prosternum is hard, resembling a 
bone. In other instances these parts are both of the 
same substance. 

1. The sternum or breast-bone of insects consists 
mostly of three distinct pieces ; in this resembling the 
human sternum, which is described by anatomists as 
composed originally of three bones a . Each of these 
pieces is appropriated to a pair of legs, and each of them 
at times has been called the sternum : thus in Elater the 
prosternum, in the Cetoniadce the mesosternum, and in Hy- 
drophilus the metasternum, have been distinguished by this 
name. Our business is now with the first of these pieces, 
the sternum of the antepectus or prosternum b : this is the 
middle longitudinal ridge of the fore-breast, which passes 
between the arms, when elevated, extended, or otherwise 
remarkable. It is most important in the Coleoptera Or- 
der, to which my remarks upon it will be chiefly con- 
fined. In these it is sometimes an elevation, and some- 
times a horizontal process of the fore-breast. If you 
examine the great Hydrophilus (H. piceus), at first you 
will think that there is only a single sternum common to 
all the legs; but if you look more closely, you will per- 
ceive between the head and the arms a triangular vertical 
process, with a longitudinal cavity on its posterior face, 
which receives the point of the mesosternum that passes 
between the arms c : this vertical piece is the real pro- 
sternum, and not the other, which really belongs to the 
alitrunk. In this case the elevation of the prosternum is 
before the arms; in others.it is between them, as you 

a Monro On the Bones, 160. b Plate VIII. d'. 

c Ibid. Fig. 7. d'. 



EXTERNAL ANATOMY OF INSECTS. 5i5 

may see in a Chinese chafer (Mimela K.), which imi- 
tates the external appearance of a quite different tribe a ; 
in others again it is behind them, as in most of the Lamel- 
licorn beetles. In the common dung-chafer (Geotrupes 
stercorarius), it is a hairy process, which, when the head 
is bent downwards, is received by a deep cavity of the 
mesosternum. The Dynastidce MacLeay may always 
be known by a columnar presternum rising vertically be- 
tween the arms and the medipectus. Lastly, in other 
tribes there is a prosternal elevation both before and be- 
hind the arms, as in Cerambyx thoracicus, dimidiatus, and 
affinities. Of the second description, those that have a 
less elevated horizontal presternum, the point in most is 
to the anus, but in some to the head, : thus in Carabus L. 
it is generally a subspathulate flat piece, the point of 
which slides over the mesosternum, or covers it; but in 
Harpalus megacephalus Latr. b , one of this tribe, though 
similarly shaped, its point is to the head. These hori- 
zontal prosterna vary in their termination. In that of 
Carabus L. the apex is obtuse ; in that of Elater, above 
described c , and Dytiscus it is acute -, in Prionus lineatus, 
Spencii K., &c, it is bilobed; and in Buprestis variabilis, 
attenuata, &c„ obsoletely trilobed. With regard to the 
other Orders no striking features of this part are observ- 
able, except in some Orthoptera. In Acrida viridissima 
K. {Locusta F.) it is represented by two long filiform ver- 
tical processes ; and in Locusta Leach by a single coni- 
cal horn d , mistaken by Lichtenstein for a process of the 

a Kirby in Linn. Trans, xiv. t. iii,/. 4. i. 

b It is doubtful whether M. Latreille's Harpalus megacephalus is 
synonymous with Carahus megacephalus Fab. Coinp. Gen. trust, et 
Ins. i. 206. with Syst. Eleuth. i. 187. 95. 

c Vol. II. p. 317—. d Peate VIII. Fig. 11. b, 

yoL. in. 2 n 



54:6 EXTERNAL ANATOMY OF INSECTS. 

throat a . In one instance, Gryllotalpa, this part is a long- 
piece between the arms, shaped like the human thigh- 
bone or tibia, being more slender in the middle and 
widest at the ends, and which is of a much harder sub- 
stance than the rest of the antepectus, and forms the 
lower termination of a singular machine which will be- 
fore long be noticed. In many bugs (Cimicidce), instead 
of being elevated, the three portions of the sternum are 
hollowed out into a longitudinal groove, in which the 
promuscis when unemployed reposes. 

The most conspicuous and remarkable appendages of 
the manitrunk, are the brachia or arms. I shall not, 
however, enter into the full consideration of these, as they 
consist numerically of the same parts, till I treat of the 
legs in general. Here it will only be necessary to assign 
my reasons for calling them by a distinct denomination. 
In this I think I am authorized, not only by the example 
of Linne, who occasionally found it necessary to do this b , 
and more particularly by the ancient notion that this 
pair of organs in insects were not to be reckoned as legs , 
but likewise from their different position and functions. 
They are so inserted in the antepectus as to point towards 
the head, whereas the other two pair point to the anus. 
With regard to their functions, besides being ambula- 
tory, and supporting the manitrunk in walking, they are 
applied to many other purposes independent of that of- 
fice, — thus they are eminently the scansory or climbing 
legs in almost all insects ; in most Carabi L., by means 



a Linn. Trans, iv. 53. b Syst. Nat. i. Cancer. Scorpio. 

c Moses, when he describe sinsects as going upon four legs, evi- 
dently considers the anterior pair as arms ; Bochart does the same. 
Levit. xi. 20—. Hierozoic. ii. 497. 



EXTERNAL ANATOMY OF INSECTS. 547 

of the notch and calcar a , they are prehensory legs ; in 
Scarites belonging to that tribe, the Lamellicorn beetles, 
and the mole- cricket, they are fossorious legs, or proper 
for digging b ; in Mantis, Nepa, and some Diptera, they 
are raptorious, or fitted to seize and dispatch their prey c : 
they are used also by many insects to clean their head, 
eyes, and antennae, &c. For many of these purposes 
they cannot be fit without: a structure different from that 
of the other legs, which renders it a matter of as great 
convenience in descriptions to speak of them and their 
parts under different names from those of the legs, as it 
is of the arms of man ; on this account it is that I propose 
to give to the fore-leg and its part the names by which 
the analogous parts, or what are so esteemed, in the hu- 
man species are distinguished; — when spoken of in com- 
mon with the other legs, they may still be called the fore- 
legs. 

* * Alitruncus. The alitrunk is the posterior segment 
of the trunk, which below bears the four true legs, and 
above the organs for flight or their representatives. In 
treating of this part we may consider its insertion or ar- 
ticulation, its shape, composition, substance, motions, and 
organs. 

i. With regard to its insertion, or articulation with the 
manitrunk and abdomen, it may be observed that it is 
attached to both by its whole circumference by means of 
ligament ; in the Coleoptera, Orthoptera, and Heteropte- 
rous Hemiptera being received by the posterior cavity of 
the prothorax, the shield of which in these Orders, espe- 

* Plate XXVII. Fig. 31 . b Plate XV. Fig. 5, 6. 
c Samouelle t. v. /. 4. 

2 N 2 



548 EXTERNAL ANATOMY OF INSECTS. 

cially the last, almost covers and conceals it ; but in the 
remaining ones it is merely suspended to it. In the 
former also, especially in the Coleoptera, it seems more 
separate and distinct from the manitrunk than from 
the abdomen, and more independent of its motions 
than of those of the latter part : but in the Hymeno- 
ptera and Diptera its greatest separation is from the 
abdomen in both respects. In many insects, as in the 
Lamellicorn beetles, the mole-cricket, &c, the mani- 
trunk terminates posteriorly, drawing a line from the 
base of the prothorax to the antepectus, in an oblique 
section ; in other tribes, as in the Cerambyx L., the 
Predaceous beetles, &c, the section here is often vertical, 
but in the alitrunk the anterior one is always verti- 
cal, while the posterior, by which it articulates with the 
abdomen, in the Orders with an ample thoracic shield, is 
oblique, so that the pectoral portion is more ample than 
the dorsal. 

ii. As to its composition, the alitrunk is usually much 
more complex than the manitrunk ; for, besides the in- 
struments of motion, it consists of numerous pieces. It 
may be regarded as formed of two greater segments, the 
first bearing 'he elytra, or the primary wings, and the 
intermediate legs ; and the second, the secondary wings 
and the hind legs. 

1. Collare a . The first segment of the alitrunk is the 
middle piece of the whole trunk, and therefore, when 
spoken of per se, may be called the meditruncus. It 
consists primarily of an upper and lower part, which 
in the table are denominated the mesothorax and the 

' Plate IX. g . 



EXTERNAL ANATOMY OF INSECTS. 549 

medipectus. The first piece in the former that requires 
notice is the collar. I formerly regarded this piece, 
which is peculiar to the Hymenoptera, Diptera, and one 
tribe of the Neuroptera, as the representative of the pro- 
thorax in the other Orders, and this opinion seems at this 
time very generally adopted, but subsequent observa- 
tions have caused me to entertain considerable doubts 
of its correctness. Many other Entomologists have 
thought it improper to distinguish these parts by the 
same name a . Much, however, may be said on both 
sides of this question, and I shall now lay before you the 
principal arguments that may be adduced in defence of 
each opinion, beginning with those that seem to prove 
that the collar is the analogue of the prothorax. First, 
then, the collar, like the prothorax, is placed precisely 
over the antepectus, and being placed in the same situa- 
tion, on that account seems entitled to the same denomina- 
tion ; especially as in some genera, for instance Chlorion 
F., it assumes the very semblance and magnitude of a 
thoracic shield, and is separated from the mesoihorax by 
a considerable incisure. Again, in some cases that have 
fallen under my own observation, the collar is endued 
with some degree of motion distinct from that of the 
alitrunk, since in Pompilus and Chrysis the animal can 
make the former slide over the latter in a small degree. 
A third and last argument is, that no prophragm is 
formed from the collar : insects that have a thoracic shield 
are generally distinguished by having the anterior margin 
of the dor solum deflexed so as to form a septum, called in 

a Latreille Organization &c, 199. Chabrier Sur le Vol des Ins. 
c. i. 412. c. iv. 54, &c. 



550 EXTERNAL ANATOMY OF INSECTS. 

the table the prophragm, which enters the chest and se- 
parates the cavity of the mesothorax from that of the pro- 
thorax ; now in Hymenoptera this septum is a process 
of the piece behind the collar, and excludes it from 
having any share in that cavity. These arguments at 
first sight seem to prove satisfactorily the identity of the 
collar and prothorax. But audi alteram partem, and I 
think you will allow that the scale containing the claims 
of the collar to be considered as a piece sui generis, dips 
much the lowest. And, first, I must observe, that 
though in Hymenoptera the collar seems to replace the 
prothorax by its situation, yet it is in fact a part of the 
alitrunk ; for, if the manitrunk be separated from the lat- 
ter, the collar remains, in most cases, attached to it a , 
while the aidepectus and arm, with the ligament that covers 
its cavity above, the real representative of the prothorax, 
are easily removed, and this in recent individuals: as a 
further proof of this, I must request you will examine a 
neuter Mid Ma ; you will see that in this the collar is 
not separated from the alitrunk in any respect, but forms 
one piece with it, while the antepectus is distinct and 
capable of separate motion : further, the action of the 
collar is upon the alitrunk, it being of essential import- 
ance in Might, whereas the prothorax is of no other im- 
portance than as a counterpoise to that part 5 . A further 
argument to prove the distinction of these parts may be 
drawn from the case of Xylocopa, a kind of bee. In this 
genus the collar forms a complete annidus or segment of 

a In CMorion, Ammophtia, &c, this part separates more readily 
from the alitrunk. 

b Chabrier Sur le Vol des Ins. c. i. 413-. c. iv. 54. This author 
seems to regard the collar as something peculiar to Hymenoptera. 



EXTERNAL ANATOMY OF INSECTS. 551 

the body : now, if it really represented the prothorax, 
the under side of the segment, as in those Coleoptera in 
which no suture separates the upper from the lower part 
of the manitrunk 3 , should represent the antepectus, and 
have the arms inserted in it; but in the case before 
us there is a distinct antepectus bearing the arms received 
by the socket formed by this annulus. But the most 
powerful argument is the fact that some insects have 
both the prothcn^ax and collar, a circumstance that com- 
pletely does away every idea of their identity. If you 
examine the common hornet [Vespa Crabro), or any 
saw-fly {Tenthredo L.), you will find, as was before inti- 
mated, that the real covering of the cavity of the mani- 
trunk is a ligamentous membrane, which properly re- 
presents the prothorax. In another genus of the same 
order (Xiphydria Latr.), the sides of the antepectus turn 
upwards and nearly form a horny covering distinct from 
the collar b , the ligamentous part being reduced to a 
very narrow line, and in Fcenus the dorsal fissure is quite 
filled up, so that in this the manitrunk is perfectly di- 
stinct, and exhibits both prothorax and antepectus of the 
usual substance. In Nomada likewise, N. Goodeniana K. 
was the species I examined, there is a short minute pro- 
thorax besides the collar. Next let us turn our attention 
to the Diplera; if you examine the common crane-fly 
(Tipula oleracea), you will find, first, a regular short 
prothorax, to which the antepectus, with the arms, is at- 
tached ; and behind this also is a short collar embracing 
the alitrunk anteriorly. The next insects that I shall 
mention, as exhibiting both prothorax and collar, are the 

a See above, p. 536. b Plate IX. Fig. 14. 



552 EXTERNAL ANATOMY OF INSECTS. 

Libellulina. These are generally admitted to have the 
former of these parts*, but besides this they have also 
the latter, which is the most ample and conspicuous 
piece in the whole trunk"; intervening, as the collar 
should do, between the prothorax and those parts of the 
trunk to which the wings are attached. There is one 
circumstance connected with the subject which should 
not be overlooked. In the Hymenoptera, usually under 
a lateral process of the posterior part of the collar, is a 
spiracle or respiratory apparatus ; in the Diptera there 
is also one, though not covered by the part in question, 
in the same situation ; now this you will find precisely so 
situated with respect to the second piece in the thorax 
of Tipida oleracea, proving that this piece is the real re- 
presentative of the collar. Enough, I think, has been 
said to satisfy you that I have not changed my senti- 
ments on this subject upon slight grounds. Probably 
traces of the part in question might be detected in the 
thoracic Orders in general, in connexion with some 
vocal or respiratory organ c ; but having had no oppor- 

a Plate IX. Fig. 6. a. b Ibid. Fig. 7- g . 

c M. Chabrier (Vol. des Ins.) supposes that the humming of insects 
is produced by the exit of the superfluous air from their thoracic 
spiracles, &c. ; in Melolontha he thinks they are in the metathorax un- 
der the wings (c. i. 457 — . Plate XXII. Fig. 13. c. f . represents the 
operculum of one of those of Dytiscus marginalis) : in the Hymeno- 
ptera, in the mesothorax, near the posterior lobes of the collar (Ibid. 
459. c. iv. 50.); and in the Diptera, in the metathorax, near the 
poiser (c. i 457)- I observed myself lately, that Elophilus tenax, 
if held by the anterior part of the body, when it hummed, alter- 
nately opened and shut this spiracle. The wings during the sound 
vibrated intensely. The hum ceased and was renewed, as they were 
restrained from this motion or released from restraint j when the 
wing was moved towards the head, a different sound was emitted from 
that produced when it merely vibrated. 



EXTERNAL ANATOMY OF INSECTS. 553 

tunity, by an extended examination of living subjects, to 
verify or disprove this suspicion, I shall merely mention 
it, and conclude this head by observing, that the collar 
varies most in the Hymenoptera order, and that its most 
remarkable form is in Vespa, Cimbex, Dorylus, &c, in 
which it bends into an ample sinus that receives the 
dorsolum a . 

2. Dorsolum h . Where there is no apparent collar, 
the dorsolum (dorslet) is the Jirst piece of the mesothorax, 
and where there is one, the second; it bears the elytra 
or other primary organs of flight. It varies in the dif- 
ferent Orders, particularly with respect to its exposure. 
In Coleopterous insects it is most commonly, but not 
invariably , covered entirely by the shield of the protlio- 
rax, the scutellum alone being visible; as it is also 
in the Orthoptera (with the exception of Mantis and 
Phasma, in the first of which it is partially, and in the 
latter intirely exposed), and the Heteropterous, and 
most of the Homopterous section of the Hemiptera. 
The scutellum is likewise covered in Gerris, Hydrome- 
tra, and Velia, and the whole of the back of the alitrunk 
by a process of the prothorax in Acrydium F., Centro- 
tus, &c. But in the remaining Orders, and the tribe 
of Tettigonia in the Homopterous Hemiptera, the dor- 
solum is not hidden by the thoracic shield. It is usually 
less elevated than the scutellum; in Necrophorus, and 
some other beetles, however, the latter is most depressed. 
With regard to its substance, it is generally not so hard 

a Plate IX. Fig. 11. g. b Plates VIII. IX. i. 

c When the prothorax is separated from the elytra by a kind of 
isthmus, as in Semites, Passalas, &c, the dorsolum is more or less 
uncovered. 



551 EXTERNAL ANATOMY OF INSECTS. 

and rio-id as the scutellum, but in most Coleqptera harder 
than in the other Orders in which it is covered ; in 
the Hemiptera, except in Tettigonia, it approaches to 
membrane. As to shape and other circumstances, it 
varies in the different Orders. In the beetle tribes it 
has generally a sinus taken out of its anterior margin, 
and it approaches more or less to a trapezium ; in Blatta 
it is transverse and somewhat arched ; in Gryllotalpa it 
is nearly square, and distinguished besides on each side 
by a minute aperture, fitted with a tense membrane, 
which perhaps covers a respiratory apparatus. In the 
locusts it is more or less triangular, and in Mantis and 
Phasma long and slender. In the Hemiptera the dorso- 
lum appears to consist of several pieces, variously cir- 
cumstanced, separated by sutures, corresponding with 
which are as many ridges on the inside of the crust a . 
In the Libellulina it is rhomboidal b ; in Panorpa nearly 
hexagonal ; in the Ephemerina it is ample and oblong ; 
in Sialis and the Trichoptera this part is represented by 
three subtriangular pieces, the scutellum constituting a 
fourth, with the vertices of the triangles meeting in the 
centre c ; in the Lepidoptera the part in question is large, 
and receives the scutellum into its posterior sinus d . The 
Hymenoptera usually exhibit a very ample dor solum ^ 
mostly subtriangular with the vertex rounded or trun- 
cated, and pointing in some {Vespa L.) to the head e , 
and in others {Apis) to the anus ; in the Diptera, except in 
Tipula, the parts of the mesothorax are not separated by 
any suture, but only indicated by impressed lines orchan- 

a Plate VIII. Fig. 16. 20. i'. h Plate IX. Fig. 7- i. 

c Ibid. Fig. 10. i. k' . rt Ibid. Fig. 1. i. k' . 

c Ibid. Fig. 11. i'. 



EXTERNAL ANATOMY OF INSECTS. 555 

nels ; in the genus last mentioned, however, the dorso- 
lum is distinct, subrhomboidal, and received by an angu- 
lar sinus of the scutellum, which last, I think, is not the 
part that has usually been regarded as entitled to that 
denomination ; for this opinion I shall soon assign my 
reasons. 

3. Scutellum*. Some writers on the anatomy of in- 
sects, looking, it should seem, only at the Coleoptera and 
Orthoptera, have regarded the dor solum and scutellum as 
forming only one piece b , and others have affirmed that 
the Lepidoptera and subsequent Orders have no scutel- 
lum . But as we proceed in considering the scutellum 
in all the Orders, we shall see that both these opinions 
are founded on partial views of the subject, and that all 
winged insects have a scutellum, more or less distinctly 
marked out or separated from the dorsolum. In the Co- 
leoptera the scutellum is usually the visible, mostly trian- 
gular, piece that intervenes between the elytra at their 
base d , and which terminates the dorsolum. Some Lam el - 
licorn beetles, &c. {Scarabceidce MacLeay) are stated not 
to have the part in question (exscutellati) : but this is not 
strictly correct, for in these cases the scutellum exists as the 
point of the dorsolum covered by the prothorax, though 
it does not intervene between the elytra: in others of 
this tribe, as Cetonia chinensis, bajida, &c, it separates 
these organs at their base, though it is covered by the 
posterior lobe of the prothorax : in Meloe F., the elytra 

a Plates VIII. IX. XXVIII. k' . ■» Audoin, Chabrier, &c. 

c Olivier. He seems also to have thought that neither the Or- 
ihojrtcra nor Homopterous Hemlptera have this part. N. Diet. 
(PHist. Nat. x. 112. 

d Plate VIII. Fig. 3. k'. 



556 EXTERNAL ANATOMY OF INSECTS. 

of which are immoveable, there seems really to be no 
scutellam. Generally speaking, as was lately observed, 
but not always, it is distinguished from the dorsolum by 
being more elevated : this is particularly conspicuous in 
the genus Mater, in which it is a flat plate elevated 
from the dorsolum by a pedicle; in Sagra the latter part 
is horizontal, while the scutellum is vertical : and even in 
cases where the distinction is not so striking, these parts 
are separated either by a line, or some difference in their 
sculpture and substance. In this Order this part varies 
greatly, and often in the same tribe or genus, both 
in size and shape; being sometimes very large a , and 
sometimes very minute; sometimes very long, and some- 
times very short; sometimes nearly round, at others 
square; now oval or ovate, heart-shaped, triangular, 
acuminate, intire, bifid, &c. In the Ortkoptera, though 
less conspicuous, it still is present as a triangular eleva- 
tion of the middle of the posterior part of the dorsolum, 
with the vertex either pointing towards the head, as in 
Blatta, or towards the tail, as in Locusta Leach b . In 
the Heteropterous section of the Hemiptera (which, in 
columns of Mandibulata and Haustellata, appear to bear 
the same reference to the Coleoptera, that the Hymeno- 
ptera do to the Diptera, and the Homopterous Hemi- 
ptera to the Ortkoptera c ) the part we are considering is 
mostly very large and conspicuous, quite distinct from the 



a In Macraspis MacLeay it is often half as big as an elytrum. 

" Plate VIII. Fig. 12. It . 

c Mr. W. S. MacLeay opposes the Hemiptera to the Ortkoptera, 
the Homoptera to the Neuroptera, and the Aptera to the Coleoptera: 
but if analogous structure be made the guide, I think my arrange- 
ment will be found most correct. Hor. Entomolog. 367. 



EXTERNAL ANATOMY OF INSECTS. 557 

dorsolum, and in some (Tetyra F.) covering the whole 
abdomen, as well as the Hemelytra and the wings ; it is 
most commonly, as in the Coleoptera, obtriangular a , but 
in the last-mentioned genus it often approaches to a pen- 
tagonal shape. Though usually so striking a feature in 
this tribe, in the aquatic bugs (Gerris &c.) it is covered 
by the prothorax. In some species of Reduvius F. (R. 
biguttatus, mutillarius, lugens, &c.) it is armed with one 
or more dorsal or terminal spines. In the Homopterous 
section, where the dorsolum, as in Tettigonia F., is not 
covered by the prothorax, the scutellum, which is merely 
a continuation of that part, bears some resemblance to a 
St. Andrew's cross, and terminates in a fork b ; in Ful- 
gora, in which it is partly covered, it is merely the trian- 
gular point of the dorsolum ; in the Cercopidce, &c, whose 
dorsolum is wholly covered, the triangular scutellum is 
distinct from it ; in Centrotus, Damis, and Membracis, in 
which the prothorax is producted, and covers the abdo- 
men more or less, the scutellum is a short transverse di- 
stinct piece. In the Lepidoptera, from the difficulty of 
abrading sufficiently the scales and hairs without injury, 
it is difficult to obtain a correct idea of the part in ques- 
tion ; in the cabbage butterfly (Pieris Brassicce) it ap- 
pears to be triangular : in the humming-bird hawk- 
moth (Macro-glossum Stellatarum) it approaches to a 
rhomboidal shape c ; and in the eggar-moth (Lasiocampa 
Quercus) it is completely rhomboidal. In the Libellu- 
lina, in the Neuroptera Order, it seems to be represented 
by the posterior point of the dorsolum, which terminates 

■ Plate VIII. Fig. 20. k' . b Ibid. Fig. 16. k'. 

- Plate IX. Fig. 1. //. N. B. This is from Cossus F. 



55S EXTERNAL ANATOMY OF INSECTS. 

in something like a St. Andrew's cross a . In most of 
the other tribes of this Order the scutellum is a triangu- 
lar piece, with the vertex to the head, received between 
two pieces of the dorsolum ; in Psocus it is nearly like 
that of Tettigonia before described. In the Hymeno- 
ptera the scutellum is separated from the dorsolum, which 
it often embraces posteriorly, as the collar does in front, 
by a suture ; it varies occasionally in shape in the diffe- 
rent tribes, most commonly it is crescent-shaped, but in 
many Ichneumonidcs and others it is triangular b ; in the 
hive bee, &c, it overhangs the succeeding piece of the 
alitrunk; in Melecta, Crocisa, &c, it is armed with a pair 
of sharp teeth c ; in others [Oxybelus uniglumis, &c.) with 
one or more spines, and in some with a pair of long 
horns d . Before I describe this part in the Diptera, it 
will be proper to assign my reasons for considering a 
different piece as its representative, from what has usually 
been regarded as such, and which at first sight seems 
the analogue of what I admit to be the scutellum in the 
Hymenoptera. The dorsolum, and its concomitant the 
scutellum, belong to the first pair of the organs of flight, 
which are planted usually under the sides of the former, 
and in the case of wings, by their Anal Area, connected 
either mediately or immediately with the latter. Now, if 
you trace the sides of the piece that I have considered as 
the part in question in Hymenoptera, you will find that 
they lead you not to the base of the lower but to that of 
the upper wings'", and in the saw-flies (Tenthredo L.) 

a Plate IX. Fig. 7- k' . b ibid. Fig. 11, 15. k' . 

c Mon. Ap. Angl. i. t. vi. Apis. ** a./. 2. a a. 
d Stoll Cigales t. xxviii. /. 164. 
£ Plate IX. Fig. 12. k'. 



EXTERNAL ANATOMY OF INSECTS. 559 

you will see clearly that the Anal Area of these wings is 
attached to a process of it, a proof that it belongs to the 
mesothorax, or region of that pair. But in the Diplera, 
the part that has been usually called the scutellum is not 
at all connected, either by situation or as a point of at- 
tachment, with the wing itself, but with the lower valve of 
the alula, which is with reason thought to be the repre- 
sentative of the secondary wing of the tetrapterous Orders. 
You may see this even in the common crane-fly ( Tipidd), 
in which there is a real alula s connected by means of a la- 
teral process, terminating in ligament, with this supposed 
scutellum. If you examine further the same insect, you 
will easily find what I regard as the true one in the bi- 
lobed piece which receives the dorsohi?n, situated be- 
tween the wings, and to the sides of which they are at- 
tached. In Asilus, Tahanus, &c, this part is transverse, 
and only distinguished on each side by an oblique im- 
pressed line ; in the Muscidce it is square, and marked by 
a straight transverse one. 

4. Frcenum a . This appendage to the scutellum and 
dorsolum varies considerably in the different Orders, and 
in many cases, as you will see, is a very important part, 
being the process by which the former is mostly con- 
nected with the elytra or upper wings. In the Coleo- 
ptera, the elytra of which are nearly stationary in flight, 
and therefore less require any counteraction to prevent 
their dislocation, this part is commonly merely a process 
or incrassation of the under margin of the scutellum, 
which towards the base of the dorsolum is dilated to 
form the socket for the elytra. Its use as a countercheck 

» Plates VIII. IX. XXVIII. f . 



560 EXTERNAL ANATOMY OF INSECTS. 

in this Order is best exemplified in the common water- 
beetle (Dj/tiscus marginalis). This at the inner base 
of the elytra has a membranous fringed alula resembling 
those of Diptera ; to the lower fold of this the extremity 
of the frcenum is attached, which forms a right angle with 
the scutellum, and the upper fold is attached to the base 
of the elytrum a . The object of this appendage is pro- 
bably to prevent the dislocation of these organs, which 
seems to indicate that they are used more in flight than 
those of other beetles. The Blattce also, in the next Or- 
der, have a winglet attached to the anal area of the teg- 
mina. The frcenum, as in the preceding Order, lies un- 
der the margin of the scutellum and dorsolum, but which 
here forms one uninterrupted transverse line ; it is near- 
ly vertical, and is attached to the alula. The structure 
is not very different in the other Qrtlioptera b , but the 
frcenum is surmounted or strengthened by one or two 
ridges ; in Mantis it runs from the scutellum in an an- 
gular or zigzag direction — but in all it is attached im- 
mediately to the tegmen. In the Heteropterous Hemi- 
ptera it is represented by the narrow bead adjacent to the 
scutellum on each side c , which dilates into a flat plate as 
it approaches the Hemelytrum, with the Anal Area of which 
it is connected. But the Homopterous section of the Order 
in question furnishes examples of the most remarkable 
structure of this countercheck, which proves that it is real- 
ly, what its name imports, a bridle. If you examine the 
great lanthorn-fly (Fulgora latemaria), or any species of 
Tettigonia, &c, you will find adjacent to the scutellum 

a Plate XXIII. Fir.. 6. e". b p LATE yill Fig. 12. V . 

£ Ibid. Fig. 20. I. 



EXTERNAL ANATOMY OF INSECTS. 561 

or parallel with it, on each side a flat plate ; and from the 
angle of that part in the first case, and from one of its 
processes in the last, you will further perceive a ridge or 
nervure which runs along this plate, in one forming an 
angle, and in the other being nearly straight, to the base 
of the tegme?i, where it becomes a marginal nervure to a 
membrane that is attached to the posterior part of the 
base of the Anal and Costal Areas; and that this marginal 
nervure, like a trachea, consists of a spiral thread, or 
rather of a number of cartilaginous rings connected by 
elastic membrane a , and consequently is capable of con- 
siderable tension and relaxation, as the tegmen rises and 
falls in flight. In the Lepidoptera it appears to be a 
short piece overhung by the scutellum, which as it ap- 
proaches the base of the wing is dilated. In the Libel- 
lulina, to go to the Neuroptera, it has the same kind of 
elastic nervure connected with the Anal Area of the wing 
which I have just described in the Homopterous Hemi- 
ptera ; another nervure, in JEshna at least, appears to 
diverge upwards from the scutellar angle to the Interme- 
diate Area b : a structure little different distinguishes the 
rest of the Neuroptera, and even the Trichoptera. In the 
Hymenoptera this part varies somewhat ; in the majority 
perhaps of the Order, as well as in the T>iptera, it ap- 
pears to be merely the lateral termination of the scutel- 
lum where it joins the wing; but in some tribes, as in 
Tenthredo L. (especially Perga Leach), Sirex L., and 
the Iclineumonidce, a ridge, and sometimes two, runs 
from the scutellum to the wing ; the upper one, where 

» Plate XXVIII. Fig. 11./'. 

b Chabrier Sur le Vol des Ins. c. iii. t. viii— v. B. i. 

VOL. III. 2 O 



562 EXTERNAL ANATOMY OF INSECTS. 

there are two, as in Perga, being the stoutest, and con- 
necting with the Costal Area, and the lower one with the 
Anal. 

5. Pnystega a . We learn from M. Chabrier, that in 
the common dragon-fly, a space, consisting of three 
triangles, which immediately succeeds the frcenum, af- 
fords attachment to no muscles, but merely covers aerial 
vesicles 5 . This is the part I have called the pnystega c . 
An analogous piece may be discovered in Phasma and 
Mantis in a similar situation; but I cannot trace it in 
Locust a Leach, or in the other Orders. 

Having considered the parts that constitute the meso- 
ihoraX) we will next say something upon those, as far as 
they require notice, that compose the medipectus or mid- 
breast. But first I must observe in general of the me- 
dipectus and postpectus taken together, or the whole un- 
derside of the alitnm/c, that though usually they are in 
the same level with the antepectus or under side of the 
manitrunk, yet in several instances, as the Scarabceidce 
MacLeay, the Staphylinidcc, &c. they are much more 
elevated than that part; they are also usually longer, 
very remarkably so in Atractocerus, but in Plater sul- 
catus and many others they are shorter. These parts 
are also commonly rather more elevated than the abdo- 
men, — much so in some, as Molorchus; but scarcely at all 
in others, as Buprestis, the Heteropterous Hemiptera, &c. 
In some of the latter {Tetyra J\) the abdomen seems 
the most prominent. Another observation relating- to 

o 

11 Plate IX. Fig. 7. m . 

b Chabrier Sur le Vol des Ins. c. iii. 354. 

c From Trviu to breathe and Hya to cover. 



EXTERNAL ANATOMY OF INSECTS. 563 

this part must not be omitted, namely, that though in 
many cases the mcdipectus and postpectus are perfectly 
distinct and may be separated, yet in others, as for in- 
stance the Lamellicorn beetles, the Hymenoptera and 
Diptera, &c, no suture separates them; so that though 
the upper parts, the mesothorax and metathorax, are se- 
parable, the lower ones just named are not so. 

6. Peristethium*. The first piece of the medipectus is 
what I have called, after Knoch, the peristethium h . This 
immediately follows the antepectus ; on each side it is 
limited by the scapulars, and behind by the mid-legs and 
mesosternum. Its antagonist above is usually the dorso- 
lum. In the Coleoptera Order it varies occasionally, 
both in form and magnitude, but not so as to merit par- 
ticular notice, except that both are regulated by the sca- 
pulars — if these are small, the peristethium is ample; and, 
vice versa, if they are large it is small. In all the fol- 
lowing Orders, except the Hymenoptera, it is equally 
inconspicuous, but in them it is often more remarkable. 
I have a Brazilian species of Cimbex (C. mammifera 
K. MS.) which appears undescribed, in which this part 
swells into two breast-like protuberances, terminating 
posteriorly in membrane, as if it had separate motion : in 
the golden -wasps (Chrysis L.) it is anteriorly concave to 
receive the coxce of the mid-legs ; and in Stilbwn, of the 



a Plates VIII. IX. n. 

b At first I had named this piece the antecosta, and the mesoste- 
thium the postcosta ; and there is certainly some analogy between the 
thorax of insects, consisting of several pieces that follow each other, 
and the vertebral column ; between their three sternums and the ster- 
num, and between their other pieces and the ribs of vertebrate 
animals. Comp. Chabrier, ubi supr. c. iv. 49. note 1. 
2 o 2 



564- EXTERNAL ANATOMY OF INSECTS. 

same tribe, it is armed with one or more conical obtuse 
teeth. 

7. Scapularia*. The scapulars are situated between the 
coxa of the mid-legs and the base or axis of the upper 
organs of flight, and they seem to act as a fulcrum to each. 
In the Coleoptera Order they are most commonly qua- 
drangular or subquadrangular, often divided diagonally, 
and sometimes transversely, by an impressed line ; the 
posterior partj which is usually the most elevated and 
often has an uneven angular surface, is that which in- 
tervenes between the coxae and elytra : where the former 
are short, as in the Capricorn beetles, the scapulars are 
long; and where they are long, as in the Petalocerous 
ones, the latter are short. The anterior part is that 
which forms the lateral limit of the peristethium, upon 
which it often encroaches : this part, in conjunction with 
the dorsolum above, and the last-named part below, 
forms the kind of rotula that plays in the posterior aceta- 
bulum of the manitrunk, as the head does in the anterior 
one. In the flower-chafers (Cetonia F.) the scapulars 
are very thick and elevated, and interpose between the 
posterior angles of the prothorax and the shoulders of 
the elytra, which is one of the distinguishing characters 
of that tribe : in this case the lower angle of the scapular 
connects with the coxa of the mid-leg, and the upper 
angle with the axis of the elytra ; and the most elevated 
and thickest part of the scapular is about midway between 
the two. This robust structure seems to indicate that 
the scapular has to counteract a powerful action both of 
the leg and elytrum. In the Orthoptera the scapulars 

a Plates VIII. IX. o. 



EXTERNAL ANATOMY OF INSECTS. 565 

are usually divided into two parallel pieces, corresponding 
probably, though more distinct, with the two parts late- 
ly noticed of those of the Coleoptera: the upper side of 
the socket of the mid-leg is common to the base of both 
these pieces, but the articulation of the tegmen is chiefly 
with the anterior one. In the grasshoppers, locusts, &c. 
(Grylhis L.) in which tribe this leg is nearly opposite to 
that part, the scapular inclines but little from a vertical 
position 3 ; but in the praying- insects (Mpntis), spectres 
(Phasma), and cockroaches (Blatta), in which the in- 
sertion of the mid-legs is behind that of the tegmina, it is 
nearly horizontal. In the Heteropterous Hemiptera the 
anterior part of the scapular is covered by the antepectus, 
and separated by a ridge, more or less pronounced, from 
the open part ; the whole is of an irregular shape, and 
nearly parallel with the -para-pleura. In the Homopterous 
section it likewise consists of two pieces, and sometimes 
of more. Thus in Tettigonia F. it is bilobed, and be- 
tween it and the coxa two small pieces are inserted b . In 
some others, lassus Lanio F., &c, it is not very unlike 
the scapular in Coleoptera, being subquadrangular and 
divided diagonally. In the Neuroptera this part and the 
parapleura are parallel, and placed obliquely c . In the 
common dragon-fly (JEshna viatica) the former forms 
nearly a parallelogram d , which is not divided by any 
ridge or channel, but its lower half is separated into two 
unequal parts by a black longitudinal line, opposed to 
which on the inside is a ridge. The mid-leg in these is 
connected with the scapular by the intervention of a 

a Plate VIII. Fig. 12. 13. o. z'. b Ibid. Fig. 17- o. 
u Plate IX. Fig. 8. o. z. ,l Ibid. o. 



566 EXTERNAL ANATOMY OF INSECTS. 

triangular transverse anterior piece, which in fact seems 
only marked by a black channel, to which also interiorly 
a ridge is opposed a . In the rest of the Order it is divided 
longitudinally into two parallel pieces. In Panorpa the 
posterior piece is longer than the anterior and props 
the coxa behind ; in Myrmeleon and Perla, &c, it ap- 
pears to consist of three pieces. I have not been able to 
obtain a clear idea of them in the Lepidoptera, except 
that they have more than one piece. Hymenopterous 
and Dipterous insects for the most part have no scapular 
distinct from the peristethium ; but in Cimbex, Perga, 
and other saw-flies, it seems represented by its posterior 
depressed and sometimes membranous part : in Vespa, 
&c. a small subtriangular piece, just below the base of 
the upper wing, is probably its analogue 5 . 

8. Mesosternum c . The central part of the medipectus, 
or that which passes between the mid-legs when ele- 
vated, protended, or otherwise remarkable, is called the 
mesosternum or mid-breast-bone. In the Coleoptera Or- 
der it exhibits the most numerous variations, and is 
usually the most strongly marked of any of the three 
portions of the sternum, affording often important cha- 
racters for the discrimination of genera and subgenera. 
It may be said to be formed upon three principal types — 
the first is, where it is a process of the posterior part of 
the peristethium, and points towards the anus or the 
head ; — the second, where it is a process of the anterior 
part of the mesostethium, and points only towards the 
head: in this case there is no suture to separate the 

3 Plate IX. Fig. 8. a. b Ibid. Fig. 12. o. 

c Plate VIII. Fig. 3, 13. p'. 



EXTERNAL ANATOMY OF INSECTS. 567 

medipectus from the postpectus ,- — the last type is where 
it is a ridge formed by a process both of the peristethium 
and mesostethium meeting between the legs ; an example 
of this you will see in the common dung-chafer (Geo- 
trupes Latr.). Upon the two first of these cases I shall 
offer a few remarks ; — the last affording no variation 
need only be mentioned. 

If you examine the terrestrial Predaceous beetles 
(Cicindela and Carabus L.) you will find that the periste- 
thium is usually flat, terminating towards the postpectus 
in a kind of fork, the sinus of which receives the anterior 
point of the mesostethium — this is the mesostemum ; but 
in the aquatic insects of this tribe, at least in Dytiscus 
marginalis, &c. the structure at first sight seems diffe- 
rent, for apparently the prosternum is received by the 
anterior fork of the mesostethium ,• but if you proceed to 
separate the manitrunk from the alitrunk, you will find 
that the true mesostemum of the usual form is quite 
covered by this point, which curves towards the breast, 
is longitudinally concave to receive the point of the pro- 
sternum, and permit its motion in the groove. In some 
Heteromerous beetles, as the Helopidce, &c. this part is 
anteriorly bilobed, so as to form a cavity which receives 
the point of the prosternum when the head is bent down: 
in Helops uitens {Tenebrio Oliv.) this sinus represents a 
crescent; in Cistela Ceramboides it is shaped like the 
Greek letter y; in the Lady-bird (Coccinella L.) it as- 
sumes nearly the shape of a Saint Andrew's cross ; in 
Spheniscus K. a the mesostemum is wide, concave and 
wrinkled, with an anterior and posterior sinus ; while in 

a Linn. Trans, xii. t. xxii./. 4. 



568 EXTERNAL ANATOMY OF INSECTS. 

the analogous genus Erotylus* it is convex anteriorly, 
and posteriorly more or less rounded ; in Doryphora it 
is a long, robust, subconical horn, often standing at an 
angle of about 45°, overhanging the prostemum. 

In the genus last named, though its mesosternum in its 
direction and appearance resembles that of many Peta- 
locerous beetles, yet it is separated by an evident suture 
from the mesostethium ; but in the last-mentioned tribe 
its representative is a process of the latter part : yet as 
the peristethium and mesostethium are separated by no 
suture, though in some cases a transverse channel, and 
in others merely a coloured line, marks the point where 
they may be considered as soldered together, in these 
cases the mesosternum may perhaps be said to be 
common to both. In this great family, which includes 
within its limits some of the most singular and wonder- 
ful in their structure and armour, as well as some of the 
most brilliant and beautiful of the beetle tribes, — the part 
in question, in a vast number of cases, will enable the 
Entomologist satisfactorily to trace its numerous groups, 
not only where it rises or stretches out into a horn or 
ridge, but even often where it is merely a flat space be- 
tween the mid-legs. I shall notice some of its most 
striking variations in this tribe. In Phanceus Jestivus, 
and in Macraspis and Chasmodia MacLeay, it is elon- 
gated horizontally, with the apex curving upwards ; in 

a A remarkable instance of analogy is afforded by this genus. In 
Erotylus there are two groups ; one distinguished by gibbous elytra, 
and the other by flatter ones. The same distinction is observable in 
Spheniscus ; for to this genus belongs Helops fascial us Oliv., which re- 
presents the flat Erotyli, and even individually Erotylus trifaxc'tahm 
Oliv., E.fasciatus F, 



EXTERNAL ANATOMY OF INSECTS. 569 

Anoplognathus it is horizontal, straight, and figures an 
isosceles triangle ; in Cetonia suturalis, vitticollis, &c. 
it is very long, passing between the arms and nearly 
reaching the head ; in C. marmorea, Lanius, &c. it is a 
lofty, robust, conical prominence ; and in many Jtute- 
lidce, especially those with striated elytra, it is pyramidal 
or four-sided ; it varies also in its termination, particu- 
larly in the Cetonia dee ,- and even where there is little or 
no elevation of it, as in the Scarabaidce MacLeay, it is 
often terminated anteriorly by lines that vary in their 
angle or curvature. The genus Copris, as restricted by 
Mr. W. S. MacLeay, may from an inspection of this 
circumstance be divided into several families. Thus in 
C. Molossus and affinities its termination represents the 
letter ^ reversed, or a triangle surmounted by a mucro ; 
in C. orientalis, &c, it ends in an acute-angled trian- 
gle ; in C. lunaris, &c. in an obtuse-angled one ; and in 
C. lacchus, &c, in the segment of a circle. 

The part we are considering is not so important in 
the other Orders. In the Orthoptera, however, it is occa- 
sionally remarkable. In Acrida viridissima (Locusta F.) 
attached to the anterior margin of the peristethium are 
two long triangular pieces which appear to represent this 
part ; in the kindred subgenus, Conocephalus a , it is a 
single piece bifid at the apex ; in Gryllotalpa it is a very 
elevated hairy ridge ; and in Locusta Leach, it is a flat 
anterior process of the mesostethium. In the Heteropte- 
rous Hemiptera this part is often merely a portion of 
the channel in which the promuscis reposes ; but some- 
times, as in Edessa F., it is an elevated piece varying 

* I would restrict this name to the conical-headed Locusta; F, 



570 EXTERNAL ANATOMY OF INSECTS. 

in its termination. In the remaining Orders, as far as I 
have had an opportunity to examine them, it can 
scarcely be said to exist separately from the medipectus, 
except that in Tipula Latr. a bipartite subtriangular 
membranous piece seems to be its analogue. 

We are now to consider the last segment of the ali- 
trunk, which, as a whole, may be denominated the po- 
trwicus ; it bears the second pair of the organs of flight, 
and the last pair of legs. The upper side of this is the 
metathorax, and its lower side the postpect/us. 

9. Postdorsolum a . The first external piece of the 
metathorax is the postdorsolum, which presents itself 
under very different forms and circumstances in the dif- 
ferent Orders. In the Coleoptera it is intirely covered 
by the dorsolum and scutellimi j it is generally more or less 
of a membranous substance, or partly membranous and 
partly corneous, which enables it to yield more to the 
action of the wings in flight; it is usually an ample 
transverse piece with tumid sides b ; but in the Scarabceidce 
MacLeay, it is short though very wide; and in Cychrus, 
and probably other apterous beetles, it is extremely mi- 
nute and almost obsolete. In the Orthoptera Order, I 
observe once for all, the part in question, as well as 
the postscutellum and postfrcenum are mere counterparts 
of the dorsolum, scutellum, and framum, except that in 
some cases they are larger c . In the Heteropterous He- 
miptera at first sight it would appear that all the parts of 
the metathorax were altogether wanting or absorbed 

a Plate VIII. IX. t' '. Linn, Trans, xi. t. ix. /. 16. c. 

b Plate VIII. Fig. 3. t . 

c Ibid. Fig. 12. Comp. i',k',l', with t', u' , v. 



EXTERNAL ANATOMY OF INSECTS. 571 

in the ample scutellum ; but if you remove this with care, 
you will find under it their representatives, its lower sur- 
face being hollowed out to receive them. The postdor- 
solum appears in these as a transverse obtusangular band ; 
in the Nepidte, Notonectidce, &c. the three parts of the 
metaihorax seem united into a single plate, emerging 
laterally from under the scutellum below the frcemim ; in 
which, however, some traces of a distinction between 
them may be discovered. In the Homopterous section 
the Fulgoridce exhibit these pieces very distinctly, cover- 
ed only at the base by the mesothorax : but in Tettigonia 
they are not so easily detected ; they exist however as a 
narrow strip or band, almost concealed by that part. 
As to the Lepidoptera Order, in Pieris Brassicce at least, 
the postdorsolum is represented by a pair of nearly equi- 
lateral triangles whose vertexes meet in the centre of the 
metathorax, and between which and the scutellum is a 
deep cavity; but in Macroglossum Stellatarum and La- 
siocampa Quercus, there appears to be also a central 
transverse piece between them. In the Neuroptera there 
is no material or striking difference between the parts of 
the mesothorax and metathorax a . In the Hymenoptera 
more variety occurs in this part. In the saw-flies, &c. 
(Tenthredo L.) the postdorsolum is a transverse piece 
covered by the scutellum; in the Ichneumonidce it is 
smaller, but not covered ; in the Vespidce it is apparent, 
transverse, and with the postscutellum obtusangular b ; in 
Apis it is overhung by the scutellum. The Diptera exhibit 
some variations in this part. In Tipula it consists of 
three pieces placed transversely, the central one qua- 

■< Plate IX. Fig. 7- I. b Ibid. Fig 11. t' . 



572 EXTERNAL ANATOMY OF INSECTS. 

drangular, and the lateral ones roundish ; in the Asilida 
and most others of this Order, with the postscutellum, it 
forms a segment of a circle a , sometimes armed with a 
pair of spines, as in Stratyomis F., and is what has been 
usually regarded as the real scutellum, though, as I have 
endeavoured to show, not correctly b . 

10. Postscutellum . The postscutellum bears the same 
relation to the postdorsolum that the scutellum does to the 
dorsolum, but it is seldom, if ever, a distinct piece. In the 
Coleoptera it is represented by the longitudinal narrow 
channel that terminates the postdorsolum towards the 
anus d : this usually figures an isosceles triangle with the 
vertex truncated or open; but ii Copris the triangle is 
equilateral. In the other Orders it is little more than 
the central posterior point of the postdorsolum e . 

11. Postfrcenum f . The part now mentioned is much 
more important than the preceding one, and must not be 
passed over so cursorily. In the Coleoptera it usually 
presents itself under the form of two large and usually 
rather square pannels, the disk of which is convex, but 
the rest of their surface unequal, which are situated one 
on each side of the postscutellum & ; under the anterior 
outer angle of these is the socket or principal attachment 
of the secondary wings, and their basal margin is at- 
tached to their outer side ; posteriorly behind the vertex 
of the postscutellum the postfrcenum is crowned with a 
ridge or bead, below which it descends vertically or 
obliquely to the adomen ; this ridge often turns upwards, 

* Plate IX. Fig. 19, 20. t . b See above, p. 558—. 

c Plates VIII. IX. u. J Plate VIII. Fig. 3 u'. 

e Ibid. VIII. Fig. 12. u. Plate IX. 7- W. 
1 Plates VIII. IX. v , s Plate VIII. Fig. 3. v. 



EXTERNAL ANATOMY OF INSECTS. 573 

and proceeds towards the middle of the basal margin of 
the wing. In the Petalocerous beetles the part in ques- 
tion is usually more or less hairy ; but in many others, 
as the rose-scented Capricorn (Callichroma moscliatum\ 
&c. it is naked. At its side you will commonly observe 
several plates and tendons (osselets Chabr.) connected 
inter se and with the base of the wing by elastic liga- 
ments, which are calculated to facilitate the play of those 
organs. In the Orthoptera, Neuroptera, and Homopte- 
rous Hemiptera, the postfrcenum does not differ mate- 
rially from Xhefrcenum a . In the Heteropterous section 
of the last Order it is usually a transverse ridge termi- 
nating the postdorsolum, with a bifurcation where it 
unites with the wing ; but in Tetyra F. (at least so it is 
in Tetyra signata,) it is a nearly vertical piece, marked in 
the centre with an infinity of very minute folds, which 
probably by their alternate tension and relaxation let 
out and pull in the wings. Amongst the Lepidoptera it 
is not remarkable. In the Hymenoptera Order it is 
mostly represented, I think, by a double ridge or fork, 
sometimes however obsolete, but very conspicuous in the 
saw-flies, which laterally terminates the postdorsolum ; 
the upper branch, usually the thickest, going to the an- 
terior part of the base of the underwing, and the lower 
one to the posterior. You may observe something simi- 
lar in the crane-flies {Tipula Latr.) and Asilidce. A 
tendon proceeding from the point of the postscutellum 
forms a fork near its end, the upper branch of which 
connects with the anterior and the lower with the poste- 
rior valve of the winglet; the structure is a little, but not 
essentially, different in other Diptera. 

» Plate VIII. Fig. 12, 16.; and Plate IX. Fig. 7. v. 



574 EXTERNAL ANATOMY OF INSECTS. 

12. Pleura a . By this name I would distinguish the 
part which laterally connects the metathorax and post- 
pectus. It includes in it the socket of the secondary 
wings. In the Coleoptera this is a two-sided piece lying 
between the postfrcenum and the parapleural with the 
upper side horizontal and the lower vertical b — a tendon 
usually proceeds from its anterior extremity to the base of 
the wing. In the Orthoptera, Neuroptera, and other Orders, 
it is merely the longitudinal line of attachment of that 
part ; but in the genus Belostoma Latreille, related to the 
water- scorpion, it presents a peculiar structure, being a 
deep channel or demitube, filled at its posterior extremi- 
ty by a spiracle and its appendages c . 

1 3. Metapnystega d . This part, although in the table I 
have placed it as an appendage of the pleura, is not always 
confined to them, as you will soon see. It either covers 
aerial vesicles, or is the seat of a spiracle. In the Order 
Coleoptera it is of the former description. If you exa- 
mine the metathorax of the. common dung-chafer (Geo- 
trupes stercorarius), in the horizontal part of the pleura 
you will see a sublanceolate or subelliptical rather mem- 
branous silky tense plate, with its point towards the. head, 
— this is the part we are considering ; something similar 
you will find in most beetles; but in some, as Callichroma 
moschatum, it is less conspicuous. This part, as far as I 
have observed, is not so situated in any other Order, ex- 
cept in some Heteropterous Hemiptera: in Belostoma the 
channel lately mentioned is filled up at its posterior end 
by a red organ with an anterior vertical fissure, termi- 

a Plate VIII. Fig. 3. w. » Plate XXII. Fig. 14. w' . 

e Plate XXIX. Fig. 25, w\ 

d Ibid, and Plate VIII. Fig. 12.; and Plate IX. Fig. 7. k" . 



EXTERNAL ANATOMY OF INSECTS. 575 

nating behind in a conical bag : in Notonecta the pleura 
has something of a plate like that of Coleoptera, but of 
a horny substance. In the Orthoptera and Neuroptera 
this part changes its situation, if it be indeed synony- 
mous ; and as the pnystega follows the frcenum, so the 
metapnystega succeeds the postfrcenum. In the Libellulina 
M. Chabrier found that this as well as the other covered 
aerial vesicles % and it probably does the same in the 
other cases in which it occurs. In Mantis and Phasma 
in the Orthoptera it is very minute; but in Locusta 
Leach, it is more conspicuous under the form of a tense 
membrane, the surface of which is depressed below that 
of the abdomen : in Acrida mridissima K. it fills the 
sinus of the postfrcenum, and is vertical, as it is in 
JEshna. It is worthy of remark that this piece bears 
some analogy to that below the ridge of the part just 
named in Coleoptera, which descends either vertical- 
ly or obliquely to the abdomen b . A similar space, 
though often nearly obsolete, may be seen in the Hemi- 
ptera and Lepidoptera. But the Orders in which this 
part is most conspicuous are the Hymenoptera and Dipte- 
ra, and in these its aerial vessels are connected with a 
spiracle. In Tenthredo L. and Sirex L., what Linne 
named grana, from their situation, should be regarded as 
belonging to the pnystega, and whether there is any part 
representing the metapnystega I am not quite satisfied ; 
perhaps the membrane at the base of the abdomen in 
Tenthredo, and the bipartite piece, apparently its first 
segment, in Sirex c , may be its analogues : but in the great 
majority of the Order, the convex or flat piece that in- 

a Surle Vol dcs Ins. c. iii. 354. b See above, p. 572. 

c Plate IX. Fig. 15. k" . 



576 EXTERNAL ANATOMY OF INSERTS. 

tervenes between the postdorsolum and its adjuncts and 
the abdomen, and which bears a spiracle on each side, 
is the metapnystega a . This part is often remarkable, 
not only for its size, but for the elevated ridges that 
traverse it, as in Ichneumon, Chlorion, &c. In the last 
genus it is of a pyramidal shape, with the anterior part 
horizontal and the posterior vertical; it is altogether 
vertical in Vespa, Apis, &c. Amongst the Diptera, in Ti- 
pula it is nearly horizontal, and shaped like a cushion ; 
but in general in this Order it is vertical, and concealed 
under the postdorsolum^ . 

We are now to consider the parts that constitute the 
postpectus or under-side of the metathorax, and which 
bears the posterior pair of legs. 

14. Mesostethium . This part in Coleoptera is termi- 
nated anteriorly by the peristethium, scapulars, and me- 
sosternum, laterally by the parapleurce d , and behind by 
the coxae of the posterior legs e , which generally are in- 
serted transversely between it and the abdomen. It is 
commonly very wide ; but in Dytiscus L., Carabus L., 
&c.j in which the coxce and parapleurce are dilated, it is 
proportionally reduced : its length is regulated by the 
distance of the intermediate and posterior legs ; where 
these are far asunder, as in the rose-scented Capricorn 
{Callichroma moschatum), &c. it is long : but where they 
are near each other, as in the Scarabceidce MacLeay, it 
is short ; its width, however, generally exceeds its length. 
In shape it is generally subquadrangular f , though some- 

a Plate IX. Fig. 11. k" . b j bid# FlG _ 20 k". 

c Plates VIII. IX. y . d Plate VIII. Fig. 4. z. 

* Ibid. p". f i bid- y_ 



EXTERNAL ANATOMY OF INSECTS. 577 

times rhomboidal, and other forms of it occur. Between 
the hind-legs it. generally terminates in a notch or bifur- 
cation distinct from the metasternum, as in Hydrophilus, 
&c. ; in Hister there is no notch, and in many Scara- 
bmdcE it projects between the hind-legs in a truncated 
or rounded mucro; in the Vesicatory beetles, Meloe 
L., it is more elevated than the medipectus, towards 
which it descends almost vertically ; in Dytiscus L., Ca- 
rabus L., &c, this part is usually divided into two by a 
transverse sinuous channel, and in Elater by a longitu- 
dinal straight one. In many Orthopterous genera, Gryl- 
lotalpa, Acrida K., Locusta Leach, &c, the mesostethium 
consists of two pieces a . It is remarkable that in many of 
these genera, in this part, as likewise in the medipectus and 
antepectus, are one or more perforations which appear to 
enter the chest, the use of which I shall explain hereafter. 
In the Libellulina, as I shall soon have occasion to shew, 
there is a peculiar arrangement of the legs and wings, in 
consequence of which this partis placed behind the pos- 
terior ones. In the remaining Orders, the mesostethium, 
though it exists, exhibits no peculiarities worthy of par- 
ticular notice, except in some Aptera and Arachnida: 
thus, in Nirmus Anseris it is terminated posteriorly by 
a pair of transverse membranous appendages which 
cover the base of the posterior coxae ; in Scorpio it con- 
sists of two pieces, the pectines h being attached to the 
sides of the posterior one. 

15. Parapleural. The parapleura, speaking gene- 
rally, is that piece of the postpectus which, intervening 
between the pleura, mesostethium, and scapulars, is at- 

a Plate VIIT. Fig. 13. y. a f. b Plate XXVII. Fig. 50. 

c Plates VIII. IX. z'. 
VOL. III. 2 1* 



578 EXTERNAL ANATOMY OF INSECTS. 

taclied by its posterior extremity to the coxa of the hind- 
leo-s ; by means of the pleura, from which it does not 
appear to be separated by any suture, it connects the 
secondary or under-wings with the hind-legs, as the sca- 
pular does the primary ones with the mid-legs ; so that 
the direction of the parapleura depends upon the rela- 
tive situation of the legs and wings. In Coleopterous 
insects its direction is horizontal, it being generally a nar- 
row subquadrangular piece that runs straight from the 
posterior coxae to the scapular a , and usually divided into 
two unequal portions by an elevated or impressed line. 
In the palm-weevil [Calandra Palmarum) this part is 
wider than usual ; in Dytiscus marginalis, — in which ge- 
nus, as likewise in Carabus L., the coxa are incapable of 
separate motion, — it is nearly a right-angled triangle, 
and is divided longitudinally into two unequal portions. 
In the Qrthoptera Order this part usually consists of two 
equal portions, and its direction is sometimes nearly hori- 
zontal, as in Mantis and Phasma ,- sometimes forming an 
angle with the horizon, as in Blatta ,• and sometimes 
nearly vertical, as in Locusta Leach. In the two first cases 
the wings are before the legs, and in the last their po- 
sition is over them. In the Heteropterous Hemiptera 
it is parallel with the scapular, is divided into two un- 
equal portions, and its direction is more or less inclined 
to the horizon 5 . As to the Homopterous section — m.Ful- 
gora it is of a very irregular shape with an angular surface, 
and its direction from the leg to the wing is first nearly 
vertical and then horizontal : in Tettigonia it is almost 
vertical, and consists of two nearly equal portions. To 

a Plate VIII. Fig. 4, z' . b Plate XXIX. Fig. 15. z. 



EXTERNAL ANATOMY OF INSECTS. 579 

come to the Neuroptera — in the Libellulina it consists of 
two pieces, like those of the scapulars, but smaller a , and 
Its inclination is towards the head : in Panorpa also it 
resembles the scapulars both in form and other circum- 
stances b . In the remaining Orders it exhibits no very 
remarkable features. 

16. Metasternum b . The central part of the mesoste- 
Ihium when elevated or porrected, or otherwise remark- 
able, is called the metastemum. In the Coleoptera, in 
those cases, as we have seen above c , in which the me- 
dipectus and postpectm form one piece, its anterior point 
becomes the mesosternum ; but in others, as the Preda- 
ceous and Capricorn-beetles, &c, it is received in a sinus 
or fork of that part, or meets it. It is usually neither 
so remarkable nor important as the mesosternum. In 
Bolbocerus K. it is a rhomboidal elevation : in Gyrinus a 
ridge; 4xs also in many Hydrophili, in which it passes 
between the hind-legs to the abdomen, and terminates in 
a sharp point d ; and in Dytiscus its two diverging lobes 
cover the base of the posterior trochanters e . In the 
Orthoptera Order this part is not remarkable; but in 
Acrida viridissima K. it consists of three triangular pieces, 
the lateral ones being erect, and the intermediate one ho- 
rizontal: in Locusta Leach it resembles the mesosternum*. 
In the Heteropterous Hemiptera the whole mesostethium 
is elevated, and terminates at both ends in a fork, the 
anterior one receiving the point of the promuscis, and the 
posterior one that of the epigastrium .• in the Homopte- 
rous section, the Tettigonice F. have usually a distinct me- 

* Plate IX. Fig. 8. &'. b Plates VIIL IX, a f. 

c See above, p. 565. d Plate VIIL Fig. 8. a f . 

c De Geer iv. U iv.f. 3. dd. ee. f Plate VIIT. Fig, 13, a f. 
2 F 2 



580 EXTERNAL ANATOMY OF INSECTS. 

tasternal point between their hind-legs. In the remaining 
Orders there is no metasternum, or no remarkable one, 
except in one singular Hymenopterous genus, Evania, the 
parasite of the Blattce a , in which there is a forked pos- 
terior process of the mesostethium with recurved points. 

1 7. Opercula b . By this term I distinguish those 
plates, before largely described c , which cover the drums 
of male Tettigonice F. ; and likewise those called also by 
the same name by M. Chabrier d , which cover, in many 
cases, the vocal apparatus of the trunk of insects : those 
of Melolontha vulgaris he describes as situated below the 
wings, and between the two segments of the alitrunlc e ; 
and if you take this insect and remove the elytra, the 
mesothorax and scapulars, under the latter and below the 
wing you will find an oval convex plate, which is pro- 
bably the part he is speaking of; — but it is better exem- 
plified, I think, in the common Dytiscus marginalis, in 
which it is very distinct as a convex subtriangular plate 
connected with the metathorax by membranous ligament, 
covering a land of pouch, and appearing to open and 
shut at the vertex f . 

I must here observe, with regard to the Aptera and 
Arachnida, that the trunk in them is much more simple 
than in those insects that are furnished with wines. In 
the hexapods, in the former Orders, though there are 

a The history of this parasite has been traced by Dr. Reid j but 
alas ! this learned and acute observer of nature did not live to give 
his discoveries to the world: it is hoped, however, they will not be 
lost, being in most able hands. 

b Plate VIII. Fig. 18. and XXII. Fig. 13. c f. 

° VoL - IL P- 405 - d Surle Voldes Ins. c. i. 459. 

e Ibid. 457-. * p LATE xxil. Fig. 13. c f. 



EXTERNAL ANATOMY OF INSECTS. 581 

usually three pedigerous segments, there is no distinction 
of dorsolum, scutellum, &c. In the Scolopendridtz and 
Scutigera amongst the Myriapods, according to the acute 
observations of M. Savigny a , — on which, however, some 
doubt at present rests, — there is a remarkable fo